Respuesta :
d + q = 20.....d = 20 - q
0.10d + 0.25q = 3.80
0.10(20 - q) + 0.25q = 3.80
2 - 0.10q + 0.25q = 3.80
-0.10q + 0.25q = 3.80 - 2
0.15q = 1.80
q = 1.80/0.15
q = 12 <=== 12 quarters
d + q = 20
d + 12 = 20
d = 20 - 12
d = 8 <== 8 dimes
0.10d + 0.25q = 3.80
0.10(20 - q) + 0.25q = 3.80
2 - 0.10q + 0.25q = 3.80
-0.10q + 0.25q = 3.80 - 2
0.15q = 1.80
q = 1.80/0.15
q = 12 <=== 12 quarters
d + q = 20
d + 12 = 20
d = 20 - 12
d = 8 <== 8 dimes