We are given the angle A is 70.8 degrees
Sum of an angle and its supplement angle is 180 degrees.
let us say A` is supplementary angle of A
so we have A+A`=180
70.8+A` =180
A`=180-70.8
So supplement angle is A`=109.2 degrees
Two angles are complementary if sum of the angle and its complement is 90 degrees.
let us say complementary angle of A is "a".
A+a =90
70.8+a=90
a=90-70.8 = 19.2
Complementary angle of A is 19.2 degrees.