Answer:
Quarters = 7
Dimes = 5
Step-by-step explanation:
Let d = dimes and q = quarters:
d+q = 12
10d+25q = 225
Solve for d:
d = 12-q
Substitute it into the second equation:
120+15q = 225
Subtract 120 from both sides:
15q = 105
Divide by 15 in both sides
q = 7