9514 1404 393
Answer:
10 quarters
Explanation:
If we add 7 nickels so the number of quarters and nickels is the same, the value becomes 2.65 +7(0.05) = 3.00. The quarter-nickel pairs are worth 0.30, so there must be 3.00/0.30 = 10 of them.
There are 10 quarters (and 3 nickels).
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If you need an equation, you can let q represent the number of quarters. Then the number of nickels is q-7 and the total value is ...
0.25q +0.05(q -7) = 2.65
0.30q = 3.00
q = 10 . . . . there are 10 quarters
You may notice that this math matches the verbal description above.