Mary has $2.20 in dimes and nickels. If she has 10 more dimes than nickels, how many of each coin does she have?
coins number of value
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dimes n+10 .10(n+10)
nickels n .05n
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total 2.20
.10(n+10) + .05n = 2.20
Multiply through by 100
10(n+10) + 5n = 220
10n + 100 + 5n = 220
15n + 100 = 220
15n = 120
n = 8
She has 8 nickels.
she has 10 more dimes than nickels,
So she has 8+10 or 18 dimes.
Checking:
8 nickels is 40 cents and 18 dimes is $1.80,
and 40 cents plus $1.80 is $2.20.
Edwin