Jack wants to paint his house. he collected quotations from two different painters. The first painter's total cost in terms of the number of hours (x) worked was modelled as f(x) = 70 + 5x, while that of the second painter was g(x) = 30 + 15x. Jack knows that it will take more than 4 hours to paint the house so he decided to go with the first painter whose cost is cheaper when the number of hours is above 4 hours.
