Answer:
She needs 32 quarters.
Step-by-step explanation:
d = dime q = quarters
d + q = 28 so d = 28-q
0.1d + 0.25q = 5.50
0.10 * (28-q) + 0.25q = 5.50
2.80 - 0.10q + 0.25q = 5.50
0.15q = 5.50 - 2.80
0.15q = 2.70
q = 2.70 / 0.15
q = 18 quarters (she has)
50-18= 32 quarters (she needs)
