Let x be one angle and x +28 be the second angle.
X + x+ 28=90
2x = 62
X=31, x+ 28=59
So 31 & 59 are the angles
He was off by 9.5%, you just divide 5.43 by 6 then subtract that answer from 1 and you get your percentage
C=m/3.
This equation is saying the cost (c) equals the minutes (m) on the phone out of 3 people