Algebra word problem

Question

A coin bank containing only dimes and quarters has 30 more dimes than quarters. The total value of the coins is $10. How many quarters and dimes are in the coin bank?

Answer 1

d = q + 30

10d + 25q = 1000

 

Substitute!

 

10(q + 30) + 25q = 1000

10q + 300 + 25q = 1000

35q = 700

q = 20

 

d = 20 + 30

d = 50

 

There are 20 quarters and 50 dimes.