I need help on 13 it has to be standard form

Let f(x) = 3 − x . find the average rate of change of f(x) from x = a to x = a + h and simplify your answer so that no single factor of h is left in the denominator.

God's gym charges a sign-up fee of $100 plus $30 per month. write an expression to represent how much someone would pay for a membership.

Four quarts of a latex enamel paint will cover about 200 square feet of wall surface. how many quarts are needed to cover 98 square feet of kitchen wall and 52 square feet of bathroom wall