A tennis club offers two payment options. Members can pay a monthly fee of $9 plus $6 per hour for court rental time. The second option has no monthly fee, but court time costs $7.50 per hour. Answer parts a through d. a. Write a linear function that models the total monthly costs for each option for x hours of court rental time. The linear function that models total monthly cost for the first payment option is f(x)= (Type an expression using x as the variable. Use integers or decimals for any numbers in the expression.)