we need to isolate the variable by moving 8x to the left side and -31 to the right side....therefore 8x becomes a negative, -8x, and -31 a positive....so now it would look like...
-8x=9+31
then we work the right side out...
-8x=40
to get x we need to divide -8x by 8 so we do the same to the right side as well....
(79 + 93 + 91 + 68 + x) / 5 = 80 (331 + x) / 5 = 80.....multiply both sides by 5 331 + x = 80 * 5 331 + x = 400 x = 400 - 331 x = 69 <=== he would have to make at least a 69
