Supplementary angles are two angles whose values added together equal 180 degrees. so i took 180 and subtracted the existing angle (88 degrees) and the answer is the measurement of the remaining angle.
in this case 92 degrees is the measure of the remaining angle (angle 4)
if he got 84 votes 3/7 so you take 84 times 4 (i got four by subracting 3 from 7 and got the remaining votes) and you will get 336 votes. hope this helps! :)