Since, a salesman whose base pay plus commissions amounted to $53,393 last year. If his base pay was $24,650 and he made $87,100 in sales last year. We have to evaluate the rate of commission.
Let the rate of commission be 'r%'.
Therefore,
24,650 + (87,100 of r%) = 53,393






r = 33%
Therefore, the rate of commission is 33%.