Anderson earns $20 per month for completing chores around the house. Each month, the amount Anderson earns increases by $0.50. The total amount of money Anderson earns from month 3 to month 18 can be represented by this expression:
a. 20 * (18-3) + 0.50 * (18-3)
b. 20 * (18+3) + 0.50 * (18+3)
c. 20 * (18-3) + 0.50 * (18+3)
d. 20 * (18+3) + 0.50 * (18-3)
