A systems problem. You have two things and you will get two answers but you only need the one. Number of coins.
X = nickles
Y = dimes
All values in pennies.
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X + Y = 39
5X + 10Y = 330
-----------------------------------------------------------------------Multiply first equation by - 5 and add to eliminate a variable.
- 5(X + Y = 39)
5X + 10Y = 330
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- 5X - 5Y = - 195
5X + 10Y = 330
============================add
5Y = 135
Y = 27 coins ( = $2.70)
X = 12 coins ( = 60 cents)
======================The money = $3.30 so the check is valid.
Y = 27 coins
X = 12 coins
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