Answer:
Step-by-step explanation:
Let d represent the number of dimes. Then 81-d is the number of nickels and the total value in cents is ...
10d +5(81-d) = 530
5d +405 = 530 . . . eliminate parentheses
d +81 = 106 . . . . . divide by 5
d = 25 . . . . . . . . . subtract 81; number of dimes
81 -d = 81 -25 = 56 . . . . . number of nickels
There are 25 dimes and 56 nickels in the box.
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<em>Comment on the method of solution</em>
It usually works well to let the variable represent the amount of the highest-value contributor (dimes). This keeps the numbers positive as the solution progresses.