A salesperson earns commission on the sales that he makes each month. The salesperson earns a 5% commission on the first $3000 he has in sales. The salesperson earns a 7.5% commission on the amount of his sales that are greater than $3000. A. This month the salesperson had $5000 in sales. What amount of commission, in dollars, did he earn? B. The salesperson had $675 in commission last month. How much money, in dollars, did he have in sales last month?