Answer:
4 dimes and 8 quarters
Step-by-step explanation:
Let d = number of dimes.
Let q = number of quarters.
d + q = 12
10d + 25q = 240
-10d - 10q = -120
(+) 10d + 25q = 240
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15q = 120
q = 120/15
q = 8
d + q = 12
d + 8 = 12
d = 4
Answer: 4 dimes and 8 quarters