Graph x=2.5 will do anything

Omar is going on a road trip! the car rental company offers him two types of cars. each car has a fixed price, but he also needs to consider the cost of fuel. the first car costs $90 to rent, and because of its fuel consumption rate, there's an additional cost of s0.50 per kilometer driven.

Can someone me out here and the tell me the greatest common factor

Tim earns $120 plus $30 for each lawn he mows.write an iniqualityvto represent how many lawns he needs to mow to make more than $310