Answer:
8 tests
Step-by-step explanation:
Let's call the number of total math tests in a year as x. Therefore, excluding the final test, the total number of tests in a year is x - 1. Since his original average was 76, that means that the sum of his test scores without the final was 76(x - 1), and because getting a 100 on his final gets him a 79, the sum of all his scores is 76(x - 1) + 100, which will be equal to 79 * x, therefore:
76(x - 1) + 100 = 79x
76x - 76 + 100 = 79x
24 = 3x
x = 8 tests
