Question 212295
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.


{{{.8x=40}}}


{{{(.8x)/.8=40/.8}}}


{{{x=400/8=50}}}


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