How many dimes and how many quarters?

Question

Meg has 15 coins, all dimes and quarters for a total of $2.85. How many times, and how many quarters does Megan have?

Answer 1

d + q = 15

25q + 10d = 285

d = 15 - q or q = 15 - d

Suuuuuubstitute!

25(15 - d) + 10d = 285

375 - 25d + 10d = 285

-15d = -90

d = 6 dimes

q = 15 - 6

q = 9 quarters