Question 923872
A coin bank has 250 coins,dimes, quarters, worth $42.25

x + y = 250..................(1)
10x + 25y = 4225..............(2)

Multiply (1) by 25

25x + 25y = 6250.............(1)
10x + 25y = 4225.............(2)

Subtract (2) from (1)

15x      =   2025
  x      =   135
Substitute x = 135 into (1)
x + y = 250
135 + y = 250
 y = 250 - 135
 y = 115

135 dimes and 115 quarters.

Hope this helps.
:-)