Answer:
14
Step-by-step explanation:
Let n represent the number of nickels. Then the number of quarters is 36-n. The difference is ...
(36-n) -n = 8 . . . . . 8 more quarters than nickels
18 -n = 4 . . . . . . . divide by 2
14 = n . . . . . . . . add n-4 to both sides
There are 14 nickels in the jar.
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Additional comment
The problem supplies more information than is needed for a solution. You can work this as a "sum and difference" problem, as we have above, or you can work it as a "mixture" problem where the total coin value comes into play. Any two of the three given relations will give a solution.
n + q = 36 . . . . . . . number of coins
5n +25q = 620 . . . value of coins (in cents)
q -n = 8 . . . . . . . . difference in number of coins
