9514 1404 393
Answer:
 8 gallons
Step-by-step explanation:
The $2 difference in the price of a car wash is made up by the gas purchase at the rate of $0.25 per gallon. So, it takes ...
 $2/($0.25/gal) = 8 gal
to make the costs the same.
The customer must purchase 8 gallons for the total cost to be the same at both gas stations.
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 3.50g +8 = 3.25g +10 . . . . costs at each station for g gallons of gas + wash
 0.25g = 2 . . . . . . . . . subtract 3.25g+8 from both sides
 g = 2/.25 = 8 . . . . . . the way we did it above