Question 529764
Like coin problems, you have to keep track of the count of the bills and their value.
x = number of $5 bills
5x = value of the $5 bills
y = number of $10 bills
10y = value of the $10 bills
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x + y = 40
so
x = 40-y
.
5x + 10y = 260
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substitute for x
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5(40-y) + 10y = 260
200 -5y + 10y = 260
5y = 60
y = 12
.
x = 40-y
x = 28
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Check the value to determine if this is the correct answer.
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5*28 = 140
10 * 12 = 120
140 + 120 = 260
Correct.
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Answer: You have 28 $5 bills and 12 $10 bills.
.
Done.