Supplementary angles mean that two angles equal to 180°.
Let us assume the 2 angles are angle A and angle B.
Angle A is 4 times bigger than Angle B, the supplement.
Let Angle B be represented by x.
Angle A is 4x ; Angle B is x.
4x + x = 180°
5x = 180°
x = 180°/5
x = 36° This is the measure of angle B.
4x = 4(36°) = 144° This is the measure of angle A.
4x + x = 180°
144° + 36° = 180°
180° = 180°