10 less than or equal to 3x-4 less than 8

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

The anwser cause i do not understand just plez

Which of the following is missing in the explicit formula for the compound interest geometric sequence below?