Question 1012186
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F=number of $5 bills; T=number of $10 bills
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T+F=20
T=20-F Use this to substitute for T below.
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$5F+$10T=$165 . This converts number of bills to dollars.
$5F+$10(20-F)=$165 . This substitutes for T from above.
$5F+$200-$10F=$165 . Put dollars on right Fs on left and simplify.
-$5F=-$35 . Divide each side by (-$5)
F=7
ANSWER: There are 7 five dollar bills in the wallet.
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T=20-F=20-7=13
ANSWER 2: There are 13 ten dollar bills in the wallet.
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CHECK:
$5F+$10T=$165
$5(7)+$10(13)=$165
$35+$130=$165
$165=$165
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