Answer:
15
Step-by-step explanation:
The equation can be turned into a ratio (9:10). If we want to change 10 to a 6, the ratio must remain the same, and to do that, whatever we do to the 10 to get 6 must be done to the 9 as well. To change the 10, we can do 10/6, which is 1.67. Now, we do 9x1.67, which is 14.4. Since we can't have .4 of a student, we must round it up to 15.