Question

Chang has 36 coins, all dimes and half-dollars. The total value of all these coins is $12.00. How many dimes does he have?

Answer 1

The first thing we must do for this case is to define variables.
 We have then:
 x = number of dimes
 y = number of half-dollars
 We write the system of equations:
 x + y = 36
 0.10x + 0.50y = 12
 Solving the system we have:
 x = 15
 y = 21
 Answer:
 He has 15 dimes