Question 8809
Let the number of dimes by "x".
Then number of nickels is "3x"
Value of dimes is 10x cents
Value of nickels is 5(3x)= 15x cents
Dquation:
 Value of dimes + Value of nickels = 625 cents
         10x + 15x = 625
              25x  = 625
                x  = 25  (number of dimes)
               3x  = 75  (number of nickels)

Cheers,
Stan H.