How much money was he given?

[outer wave]

Gary was given some money to buy some school supplies. He spent 20% of the money on stationary, and 3/5 on books. If he had $3000 remaining; how much money was he given?

I turned 3/5 into a percentage by multiplying it by 100 making it 60%, added that by the previous percentage (20) making it 80%.

Then multiply 80% by 3000 to find out how much he spent, then add that by 3000 (since he had 3000 remaining) to find the original price which is 5400.

Is that correct?

[jolly light]

no
spent -> 80%
remaining -> 100% - 80% = 20%
20% -> $3000
1% -> $3000/20 = $150
100% -> $150 × 100 = $15000

[outer wave]

Why did you find the unit rate?

[jolly light]

wdym

[outer wave]

You divided 3000 into 20 to get $150, meaning 1% is $150. Why?

[jolly light]

cuz I want to find the original price which is 100%

after you get the 1%, to get the 100% you just simply multiply by 100

[outer wave]

@jolly light Why wouldn't you be able to add 80 percent on the 3000 to get the original price?

[jolly light]

yes you can do that too

but you still need to find out how much is 80%

[outer wave]

@jolly light Can't you just treat 80% as tax and add that onto 3000? If 3000 is the 20% remaining and the 80% is what he had before why can't you just add that onto 3000 to get the original price?

[jolly light]

like I have said before you can do that too

[outer wave]

but wasn't my answer wrong?

[jolly light]

cuz you multiplied 80% by 3000 whereas 3000 is the remaining not the original

[outer wave]

How would you do it correctly with my way?

[jolly light]

your 1st part is correct, then the following should be like
20% -> $3000
80% -> $3000 × 4 = $12000
$12000 + $3000 = $15000

[outer wave]

I see, can you say why you multiplied it by 4?

[jolly light]

cuz from 20% to 80% you need to multiply by 4

[outer wave]

ok, thanks!