Subject: Math
Name: Charles
Who are you: Parent

If you average 84 on first three test and the first score was 67. The second score was 7 less than the third score. What was the score on the second and third test.


Hi Charles.

Let the test scores be a, b and c.

Then the average is (a + b + c) / 3 which you know is 84.

You know that the first score is 67 (so a = 67) and the second score
is 7 less than the third (so b = c - 7).

Let's re-write that first expression and replace a and b with what they equal:

(a + b + c) / 3 = 84
(67 + (c - 7) + c) / 3 = 84

Do you think you can solve this last equation and find the third score?

Hope this helps,
Stephen La Rocque.