Answer:
He earns after expenses: $210
Explanation:
If 50 cars park in his lot during the day, he will earn:
50*$5= $250
But he must include expenses to know his real profit. The only expense that the problem states is the lot rent, which is $40 per day. Expenses must be subtracted from his earnings:
$250-$40= $210
On a day, he earns after expenses: $210