d+q=26, so we can say d=26-q
Then we are told:
.1d+.25q=5.15, using d found above makes this equation become:
.1(26-q)+.25q=5.15 perform indicated multiplication on left side
2.6-.1q+.25q=5.15 combine like terms on left side
2.6+.15q=5.15 subtract 2.6 from both sides
.15q=2.55 divide both sides by .15
q=17, and since d=26-q
d=26-17
d=9
So there are 9 dimes and 17 quarters.
