A car salesman receives $50 for each car sale plus 2% of the purchase price. How much must a car sell for in order for the salesperson to earn at least $500?

We simply take the amount he needs no earn ($500) subtract what he gets for each sale ($50) and divide with the percentage he gets (2% = 0.02)

500-50 = 450

450/0.02 = 22500

The salesperson has to sell a car for $22500 in order to earn $500 himself