Question

Computer Craft pays its sales associates a 15% commission on every sale. Barry sold a laptop computer for $1,900 and a printer for $300.

How much money did Barry earn on the sale of the items?

Answer 1

ok first add up the amounts what do you get??

Answer 2

wait...on every sale....isn't that two sales ?

Answer 3

yes so if they add up both amounts then multiply by .30 that will there answer

Answer 4

Multiply the sum by 0.15

Answer 5

no @mathstudent55 the Q states each sale and there are 2 sales so u multiply by .30

Answer 6

wouldn't you multiply the sum by .30

Answer 7

yes

Answer 8

were these items purchased separately ?

Answer 9

The commission is 15%.

15% of 1900 + 15% of 300 =

0.15 * 1900 + 0.15 * 300

Factor out 0.15:

0.15 * ( 1900 + 300)

15% * (1900 + 300)

In other words, take 15% of the sum.

Answer 10

thats still .30 either way it is the same answer

Answer 11

and there is no need to factor

Answer 12

If you multiply the sum by 0.30, that means you are making the commission 30% on each item. You can't add the commission percentages. You can only add the prices of the items.

Answer 13

I would just do the .30 with the sum

Answer 14

@jazzyfa30 No it's still not .30 and it never was.

Answer 15

thats the same thing i think @kelliegirl33

Answer 16

so it is just 15% of EACH sale and not 30% of the total ?

Answer 17

k so if we do one item at a time then add them together were still putting it in as .30o

Answer 18

@jazzyfa30 & @kelliegirl33
Stop writing for a minute and follow along what I am writing below.

Answer 19

Let me ask you this way.
Imagine the employee makes a 50% commission.
He sells 2 items.
Both items cost $100 each.
According to what you are saying, the commission now should be 100% of $200, right?

Answer 20

it would be half...
50% of 100 + 50% of 100

Answer 21

which would make it all half price

Answer 22

cost would be 200 and commission would be 100...right ?

Answer 23

That is correct.
But abovem regarding the 15% commission, you said that it would be 30% of the sum which in this case would correspond to 100% of $200.

Answer 24

That is correct.
But above regarding the 15% commission, you said that it would be 30% of the sum which in this case would correspond to 100% of $200.

Answer 25

what about 15% of 1900 and 15% of 300...but if you didn't factor would you get the same answer as you would by factoring ?

Answer 26

ok i get that but if we did each item 1 at a time we would still technically be puttig the answer as 30% of the overall amount do u see what im getting at??

Answer 27

In my example (50% commission) isn't
50% of 100 + 50% of 100
the same as
50% of (100 + 100) =
50% of 200?

Answer 28

oh...yes it is

Answer 29

but the answer either way would be 100

Answer 30

It';s is still not 30% of anything
15% of 1900 + 15% of 300 = 15% of (1900 + 300)
There is not 30% anywhere.

Answer 31

true

Answer 32

so don't add the percents, just the sums

Answer 33

ok but the answer will stilll be the same either way just like in your example

Answer 34

I got it now....

Answer 35

Correct.
From my 50% commission example, you are not adding the comission percentages and saying it's 100% total commssison.
Why do you keep insisting that the 15% commssions add together to make a 30% commssion?

Answer 36

30% of 2200 is not the same as 15% of 2200

Answer 37

I understand what you are saying now mathstudent....it makes sense to me now

Answer 38

yeah i understand too and @Babez_1999 ur answer is 330

Answer 39

In my example, if you added the percents of the commissions, then the commission would be 100%.

100% of the $200 in sales ($100 + $100) would be $200 in commission, but you know the commission is only $100. So you know that the percentages do not add together.

Answer 40

yea...that makes sense

Answer 41

@jazzyfa30
I know the problem, does not require factoring, but those steps above that I showed in which I factored were to prove mathematically that if you take 15% commissions of many items and add them together, it's the same as taking 15% commission of the sum.

Answer 42

After avery longgggggggggggggggg debate mathstudent proved me wrong and i actually appriciated it thanks @mathstudent55 u taught me sumn new.

Answer 43

me too :)

Answer 44

yea i see that

Answer 45

15% of 1900 = 0.15 * 1900 = 285
15% of 300 = 0.15 * 300 = 45
------(add)
330

15% of (1900 + 300)
= 15% of 2200 = 330

Answer 46

Great

Answer 47

thanks mathstudent

Answer 48

thanks

Answer 49

wlcm

Answer 50

BTW, with this, you can save a lot of time. Let's say you go to a store and every item is on sale, 10% off.
You are buying 20 items and want to find the total price. Instead of taking off 10% of each item, then adding all the dicounted prices together, you can simply just add all original prices together, then take 10% off from the sum. You only calculate a percentage once.