SOLUTION: scott spent one ninth of his allowance on newspaper, and two fifths of his allowance on a snack. if he has $2.20 left, how much does he get for an allowance?

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Question 118464: scott spent one ninth of his allowance on newspaper, and two fifths of his allowance on a snack. if he has $2.20 left, how much does he get for an allowance?
Answer by solver91311(24713) About Me  (Show Source):
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Let's say that Scott gets x cents for his allowance. We know he spent x%2F9 cents on the newspaper, 2x%2F5 cents on the snack, and he has 220 cents remaining. Assuming no additional purchases or expenditures, these three amounts must add up to his total allowance, or:

%28x%2F9%29%2B%282x%2F5%29%2B220=x

%285x%2F45%29%2B%2818x%2F45%29-%2845x%2F45%29=-220

-22x%2F45=-220

x%2F45=10

x=450 cents, or $4.50.

Check your answer:

One-ninth of $4.50 is $0.50. Two-fifths of $4.50 is $1.80.

$0.50 + $1.80 = $2.30 and $4.50 - $2.30 = $2.20.