Question

The coin box of a vending machine contains $6.20 in dimes and quarters. There are 32 coins in all. How many of each kind are there?

Answer 1

Let d and q be the number of dimes and quarters respectively.

10 cents* d+ 25 cents* q = 620 cents ($6.20 = 620 cents)
⇒ 10d + 25q = 620 (1)

On the other hand, we have: d+ q= 32 (coins) (2)

From (1) and (2), we solve the set of equations.

The final answer is d= 12 coins and q= 20 coins.