Question

Francois is rolling coins. He has 3 rolls of 40 quarters. He has 8 rolls of 50 dimes. He exchanges 2 rolls of dimes for 1 roll of quarters. How many coins, c, does Francois have? (PLEASE HELP MY TEACHER IS GONNA BE SO MAD IF I DON'T TURN THIS IN BY TOMMOROW)​

Answer 1

460

Explanation:

I'll give it a go, but I don't quite understand "he exchanges 2 rolls of dimes for 1 roll of quarters." Does he exchange them with someone else? Maybe the bank?

If he has 3 rolls of 40 quarters, then he has 3 x 40 = 120 of those coins.

8 rolls of 50 dimes is 8 x 50 = 400 of those coins.

So 400 + 120 = 520 coins.

That's before he "exchanges" anything, which is the piece I don't understand.

2 rolls of dimes ($10) for 1 roll of quarters ($10) is a fair exchange money-wise, but of course it reduces the amount of coins from 100 to 40, so 60 less coins overall. Is he exchanging those dimes with someone else, so he gives away 100 dimes and gets back 40 quarters?

Which would be this: He started with 8 rolls of dimes and 3 rolls of quarters. But he trades 2 rolls of dimes with someone for 1 roll of quarters. That leaves him with 6 rolls of dimes and 4 rolls of quarters, so just do the math again:

(6 x 50) + (4 x 40) = 300 + 160 = 460

I think that's probably the answer you're after.

Answer 2

340

steps

3 times 40 = 120 times .25 = $30

8 times 50 = 400 times .10 = $40

2 times 50 = 100 times .10 = $10

8 - 2 = 6 times 50 = 300

plus

1 * 40 = 40

300 + 40 = 340

340