Question 1176374
<br>
An informal solution uses the same calculations as the formal algebraic solution shown by the other tutor.<br>
There are 4 people, their average is 80.  Evan scoring 99, instead of what he actually scored, would raise that average to 86.<br>
The increase in the average is 6, so the increase in total points is 6*4=24.<br>
So Evan's actual score was 99-24 = 75.<br>