When two angles are supplementary angles then the sum of the angles is [tex] 180^o [/tex].
Let the supplementray angle of ∠EGB = ∠x.
So we know that ∠x + ∠EGB = [tex] 180^o [/tex]
Now to find angle x we will move angle EGB to the right side. Angle EGB is added there. So to move it we will use reverse operation. Reverse operation of addition is subtraction. So we subtract angle EGB from both sides. We will get,
∠x + ∠EGB - ∠EGB = [tex] 180^o [/tex] - ∠EGB.
∠x = [tex] 180^o [/tex] - ∠EGB
So we have got the required equation to find the angle which is supplementary to the angle EGB.
