Jamal works part-time earning $8,000 per year. He reduces his work hours by half so that he can go to school. Jamal completes his degree after 3 semesters (1.5 years) at a cost of $1,400 per semester in tuition and $500 per semester in books. What was Jamal? s investment in getting his degree?

I assume he gets paid by hour, and since he cut his ours in half he'll be earning half as much: 8000 / 2 = 4000.

He goes to school for 3 semesters which is a year and a half, so he's earning half income for a year and a half = 4000 * 1.5 = 6000

total cost of going to college per semester = tuition + books = (1400 + 500) = 1900

total cost of college for the year and a half (4 semesters) = 1900 * 3 = 5700

so, by working half hours he already reduced his income by half, making him lose 6000 in the course of the year and a half and he lost 5700 in college costs, this makes his total cost = cost of half hours + cost of college = 6,000 + 5700 = 11,700

Here the answer to your question really depends on what your teacher means by investment, if he means the opportunity cost and college cost then it's 11,700 if he means the cost of college then its 5700.