Tommy has a lawn service. He earns $25 for every lawn he mows. Which of the following represents the rate of change of his income with respect to the number of lawns he mows?
2 lawns
$12.50
2 lawns $12.50
2 lawns
$50
2 lawns $50
$
12.50
2 lawns
$ 12.50 2 lawns
$50
2 lawns