The correct answer is:
6.6 years.
Explanation:
Since he goes from making $28,000 per year to $14,000 per year, he will lose $14,000 each year that he works part-time. He intends to do this for 2 years; this will be a loss of $14000(2) = $28,000.
We will add the cost of his degree to this: 28,000+5,000 = $33,000.
He will be making $33,000 per year when he graduates. This is 33000-28000 = 5000 more per year than he made before.
To find out how many years it will take him to recover his investment, we divide the amount he loses, 33,000, by the extra amount he will make per year, 5000:
33000/5000 = 6.6