Answer:
D
Explanation:
65.8 in this equation would be the base grade if they studied for no period of time. 9.6 in this context would show how much their grade would go up by depending on (x) amount of hours.
As an example;
0 hours studied: 9.6(0) + 65.8 = 65.8
1 hours studied: 9.6(1) + 65.8 = 75.4
2 hours studied: 9.6(2) + 65.8 = 85
..and so on