Kevin gave Ben $4.90 in dimes and quarters. If 10 coins are quarters, how many coins were dimes? Which equation models this problem?

4.90•10=25d

5d+250=4.90

25+5d=4.90

0.25•10+0.1•d=4.90

i think it's 0.25•10+0.1•d=4.90

Remark

4.90 is all by itself. It is the total amount of money. It should not be multiplied or divided by anything. So A is wrong.

B: requires a decimal place somewhere in the 490. It would take quite a few dimes to make up 490 dollars. B is wrong.

C: 25 is a decimal (0.25) without a multiplication by 10 present. The 25 should not be alone in any event. C is wrong.

D: is the correct answer. It is what you must use to find out how many dimes there are. Although did not ask for it, you need 24 dimes.