The problem I'm working on is...
A truck gets 500/x
miles per gallon (mpg) when driven at a constant speed of x mph, where 40 ≤ x ≤ 80.
If the price of fuel is $2.80/gal and the driver is paid $20/hr, at what speed is it most economical for the trucker to drive?
I have been searching for similar problems in my text book and class notes but am unable to find one. I'd greatly appreciate any help or similar examples!