Plz answer here now lol

Given the function f(x) = log base 4(x+8) , find the value of f^-1(2)

Marlow is comparing the prices of two trucks rental compaines company a charges $3 per hour and an addtional $75 as serivce charges company b charges $2 per hour and an additional $85 as serivce charges

How to do this , and can some one explain