Tom sat two mental tests (each out of 10) his mean score for the test was 6 if tom scored 9 in the first test what must he have scored in the second
(9 + x)/2 = 6
This represents the average of the tests equal to 6.
Multiply both sides by 2
9 + x = 12
Find x. Check to me sure the two tests have a mean of 6.