Algebra
posted by Scott on .
Alycia's pggy bank has dimes and quarters in it. The numbers of dimes is four less than three times the number of quarters. If the total value of the coins is $7.85, how many dimes are in the piggy bank?

q = number of quarters
3q  4 = number of dimes
0.25q = value of quarters
0.10(3q  4) = value of dimes
0.25q + 0.10(3q  4) = 7.85
Solve for q, number of quarters
3q  4 = number of dimes