Question 50892
Think of:
d = number of dimes
q = number of quarters
d + q = 40 which can be: d = 40 - q
plug:
0.1d + 0.25q = 4.90
0.1(40 - q) + 0.25q = 4.90
4 - 0.1q + 0.25q = 4.90
0.15q = 0.90
q = 6
plug: d = 40 - q = 40 - 6 = 34
34 dimes and 6 quarters