Question

you bought a pair of shoes and paid 69.12. the sales tax was 8% and the shoes were 20% off. what is the original price?

Answer 1

A-80
B-58
C-60
D-64

Answer 2

im forbidden to use calculators

Answer 3

don't put in algebraic expression x-x i didnt understand it

Answer 4

Let's see... to simplify this for you, let's try trial and error.

Answer 5

For A:
80 * .20 = 16
80 - 16= 64
64 * 1.08 = 69.12

Answer 6

Well, it looks like A is our answer. Do you understand the calculations I did?

Answer 7

where you get the 1.08

Answer 8

108% for 100% + 8% to calculate sales tax.

Answer 9

But knight, what if this wasn't multiple choice?

Answer 10

We have to try working backwards

Answer 11

then its soley A

Answer 12

my teacher did the problem 5 times
came up no where near

Answer 13

over 80 below 60

Answer 14

the answer isnt as important as learning the process

Answer 15

thats where my struggle laid at

Answer 16

Ok watch.

Answer 17

For 69.12:
Our first step is to get rid of the sales tax.

Answer 18

We added the sales tax by doing what?

Answer 19

adding 20%?

Answer 20

No. The sales tax was 8%

Answer 21

multiply right?

Answer 22

By what?

Answer 23

20%?

Answer 24

No. To calculate the sales tax we multiplied 64 by 1.08

Answer 25

Because the sales tax is 8% more than the original cost.

Answer 26

We find the sales tax by multiplying by 1.08 or 108%

Answer 27

Do you understand?

Answer 28

It's the same thing as finding 8% of 64 and then adding it to 64.

Answer 29

im writing it down okok

Answer 30

Good.

Answer 31

this problem confused me by a lot

Answer 32

So, once again, how did we calculate sales tax?

Answer 33

8% more the cost so its 108%

Answer 34

We MULTIPLIED by 1.08.

Answer 35

So, if we were working backwards, how would we get rid of the sales tax? In other words, find the cost before sales tax was applied.

Answer 36

If you have no clue, I'll tell you.

Answer 37

yikes i cant think of it when going inreverse

Answer 38

never did it this way

Answer 39

Ok, so what we need to do is DIVIDE.

Answer 40

69.12/1.08 = 64

Answer 41

And voilà, we have our cost before sales tax was applied!

Answer 42

@KnightOfPentacles have you learnt algebra yet?

Answer 43

pre-algebra lol

Answer 44

i haven't entered algebra yet

Answer 45

Knight, do you understand what I did?

Answer 46

i'm trying not to frustrate anybody

Answer 47

but im trying to grasp the concept it isn't sticking to me personally :(

Answer 48

No, it's fine.

Answer 49

my teacher throw in the problem knowing that we haven't even gotten to this type of math is insane

Answer 50

So, just forget the rest of the problem.
We multiplied by 1.08 to find sales tax of 64, which was 69.12
So, working backwards,
We divided by 1.08 to get rid of the sales tax of 69.12, which was 64.
Do you understand now?

Answer 51

ooo...

Answer 52

now i get it. i bee multiplying this several ways no where near

Answer 53

i started to divide but i wasnt dividing the right things in order to get to the answer

Answer 54

Ok great. So, back to the original problem.
you bought a pair of shoes and paid 69.12. the sales tax was 8% and the shoes were 20% off. what is the original price?
For $69.12, what was the cost before sales tax was applied?

Answer 55

80 dollars

Answer 56

Nope. Try again.

Answer 57

o.o waaht

Answer 58

Remember this is before sales tax but not before the discount.

Answer 59

69.12/1.08 = cost before sales tax

Answer 60

discount goes first

Answer 61

lets try simpler numbers,
if I paid 100 for shoes AFTER 50% discount, what was the original price?

Answer 62

50

Answer 63

Thanks for the help baru. :P

Answer 64

:)

Answer 65

So how did you get 50 knight?

Answer 66

50% half of any

Answer 67

the best way to looks at it is to write out the equation of what is occuring first in words... then substitute numbers
"you bought a pair of shoes and paid 69.12. the sales tax was 8% and the shoes were 20% off. what is the original price?"

Original Price = ??
Discounted Price = Original Price - (Original Price x 20%)
Final Price = Discounted Price + sales tax
Sales tax = (Discounted Price x 8%)

so...
Final Price = Discounted Price + sales tax
Final Price = Original Price - (Original Price x 20%) + (Discounted Price x 8%)
Final Price = Original Price x 80% + [(Original Price x 80%] x 8%)
Final Price = 0.8 x Original Price + [(0.8 x Original Price)] x 0.08)
Final Price = (0.8 x Original Price) + [0.064 x Original Price]

now if Original Price = y, and Final Price = 69.12

Final Price = (0.8 x Original Price) + [0.064 x Original Price]
69.12 = (0.8y) + [0.064y]
69.12 = 0.864y
69.12/0.864 = y
80 = y

Answer 68

1/4 = 25
1/2 half
1/3 = 333
2/3 667

Answer 69

Right. So knight, what's 8% of 100

Answer 70

0.08

Answer 71

No. 8% of 100 is just 8

Answer 72

per cent means for per 100 hundred.

Answer 73

*1 hundred

Answer 74

So answer me this.
What's 2% of 100?
What about 3%?
How about 74%?

Answer 75

2.00
3.00

Answer 76

74.00

Answer 77

yup. Just forget the decimals, they can be confusing. Just 2 and 3 and 74

Answer 78

ok

Answer 79

Ok, so what is 2% MORE than 100?

Answer 80

102%

Answer 81

Good job!

Answer 82

wait a minute

Answer 83

Except it's not a percent. Just 102.

Answer 84

what's 200% of 100?

Answer 85

8 more than 100= 108 move the decimal twice to the left is 1.08

Answer 86

300

Answer 87

No. Just 200. It's not 200% more.

Answer 88

What's 150% of 100?

Answer 89

1500

Answer 90

No. Just 150.

Answer 91

oh of means multiply whoops

Answer 92

What's 125% of 100

Answer 93

125

Answer 94

Good job. Now what's 125% more than 100?

Answer 95

@KnightOfPentacles
i dont think you have understood percentages clearly, but you are close :) ... I really think you should discuss with your teacher or parents..

Answer 96

i have the process down

Answer 97

i don't do it on pc lol..