Question 212295: Kirsten spent 1/5 of her money for gasoline. Then she spent 1/2 of what she had left for a haircut. She bought lunch for $7. When she got home she had $13 left. How much did Kirsten have originally? I tried working this so X was the original, 1/5*x was the gas, 1/5x *1/2 was for haircut and -7 for the lunch subtracting each to equal 13. But I don't think its right. Maybe work it backwards with 13+7=20 then what to do with the haircut and gas?
Answer by rapaljer(4671)   (Show Source):
You can put this solution on YOUR website! I would start at the end of the trip and work backwards, like you started to do. She ended up with $13 after spending $7 for lunch. So 13+7 = 20. Prior to that, she spent half of her money on a haircut, so she must have had $40 before the haircut. Now, if she spent 1/5 of her total money on gasoline, leaving $40, then 4/5 of what she started with must have been equal to $40.
Now, see if it works. She started with $50, and she spent 1/5 of it on gas. That means she spent $10 on gas, leaving $40. Next, she spent half of her money that was left on a haircut, which would be $20, leaving her with $20. She spent $7 on lunch leaving her with $13, so it seems to check!
R^2
Dr. Robert J. Rapalje, Retired
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