a pile of 68 coins of quarters and dimes. If the value of the pile is $15.05

Question

a pile of 68 coins of quarters and dimes. If the value of the pile is $15.05, how many dimes are there 

Answer 1

You need to create a system of equations.

 

 

25q + 10d = 1505

    q +    d =     68

 

Multiply the second equation by 10, then subtract it to eliminate d.

 

Got it from there?

Answer 2

Let d = the number of dimes

Let q = the number of quarters

d + q = 68    Solve for q

       q = 68 - d

.10d + .25q = 15.05   Multiply both sides by 100

10d + 25q = 1505     Replace q with 68 - d

10d + 25(68 - d) = 1505

10d + 1700 - 25d = 1505

                      -15d = -195

                            d = 13 dimes

d + q = 68

13 + q = 68

          q = 55  quarters