Answer:
$80
Explanation:
We are given that Sam tutors math and for each hour that he tutors, he earns 20 hours and we are to find the amount of money he earns if he tutors for 4 hours.
Sam's earning is given by:
where
is the number of hours that he tutors for.
Substituting the number of hours in the above equation to get:
Therefore, Sam earns 80 dollars.