Question 150148
Your problem did not state how many students were in the class. But your first line in the solution uses the number 19. So I will assume there are 19 students.

You are told the class average is 82, that girls total was 966 and that 8 boys took the test.

So, the total points scored on the test is:
Total= girlsTotal + boysTotal
Total = 966 + 8*boysAverage

You also know the class average was 82. So the Total= 19*82 = 1558

Substitute the total and solve for boysAverage
Total = 966 + 8*boysAverage
1558 = 966 + 8*boysAverage
1558-966 = 8*boysAverage
592 = 8*boysAverage
74 = boysAverage