Question

I really need help. A shopper used some 30-cents off coupons and some 20-cents off coupons at the supermarket to get a reduction of $3.30 from her grocery bill. If she used a total of 14 coupons, how many of the 30-cents-off coupons did she use?

Answer 1

yay!

Answer 2

i got yr ans

Answer 3

0.3(5) + 0.2(9)
3.3

Answer 4

so he uses 5 coupons of 30 cents

Answer 5

wow! Thank you
can you show me all your work this? so I can try to see how your broke it down

Answer 6

lol, well i did it mentally.

Answer 7

its been 25 years since I did this stuff. I am so lost

Answer 8

lol, it happens sometimes.

Answer 9

Thanks so much, been working on this hopemwork assignment for hours

Answer 10

i workd for minutes! ^.^

Answer 11

3-4mins

Answer 12

still can you break it down for me
sowwy

Answer 13

umm, i cant.
idk how i did it..

i just usd my calc & did it mentally.

Answer 14

I just the actual first step

Answer 15

radar will help u

Answer 16

I will make an attempt to show you the steps. first I have to read the problem and see what is there.

Fact: There were 14 coupons used.
Fact 2: Only 20 cent and 30 cent coupons were use
Fact 3 the coupons added up to a savings of $3.30 savings.
I think those are the only facts we need to concern ourselves with/

Answer 17

Let x = the number of 20 cent coupons
Let y = the number of 30 cent coupons
Fact: x+y =14.
Do you follow so far?

Answer 18

yes

Answer 19

Good lets get to the savings!

20x + 30y =330 cents that tells us about the savings,,,,,,,it could also be written as:
.20x +.30y=$3.30
Is that clear?

Answer 20

yes]

Answer 21

Now lets take these two equations with only two variaBLEs (x and y) and find out how many of each coupon she used:

x+y=14 and
.2x +.3y=3.30 Which one do you want to solve for first?

Answer 22

x or y ??

Answer 23

y

Answer 24

I want to solve for y firs the number of .30 coupons.

Using the elimination method I take the first equation and multiply all terms by .2
.2(x+y=14)
.2x +.2y=2.8 I will then subtract the second equation form this
-(.2x+.3y=3.3)
-----------------
0x -.1y =-.5 Note how the x was eliminated whoooosh it is gone.
we solve for y.
-.1y=-.5 multiply thru by 10
-y=-5
y=5 Just as the previous poster said. There were 5 30 cent coupons.
Did you follow the solution part?

Answer 25

did you understand how -y=-5 became y=5 ??

Answer 26

hold on

Answer 27

hold on

Answer 28

to find x just plug the 5 for y in x+y=14 or x+5=14 solve for x

Answer 29

I'm a holdin

Answer 30

I GOT IT
: )

Answer 31

Great. Good luck.

Answer 32

Thank you so much

Answer 33

You are welcome, glad I helped.