Paul surely charges 75 dollars, and then he adds 40 dollars per hours. This means that the expression for the money he asks is
[tex] m = 75+40h [/tex]
where [tex] m [/tex] is the amount of money and [tex]h[/tex] is the number of hours.
Since [tex] h [/tex] can be at most 8, this is the case that generates the highest money, so if we plug [tex] h=8 [/tex] we have
[tex] m = 75+40\cdot 8 = 75 + 320 = 395 [/tex]
