Maribel has $1.25 in her pocket. the money is in quarters and dimes. there are a total of 8 coins. how many quarters and dimes does maribel have in her pocket? i know the answer but i don't know how to solve

0.25q + 0.10d = 1.25
q + d = 8q = 8 - d

0.25(8 - d) + 0.10d = 1.25
2 - 0.25d + 0.10d = 1.25
-0.25d + 0.10d = 1.25 - 2
-0.15d = - 0.75
d = -0.75/-0.15
d = 5 <=== there are 5 dimes

q + d = 8
q + 5 = 8
q = 8 - 5
q = 3 <=== there are 3 quarters