Study the adjoining figure and then explain why x = y

Step-by-step explanation:

y is the remote exterior angle. The remote exterior angle has the strange property that it is equal to the two remote interior angle. The two remote interior angles are the two, neither of which is the supplement of the exterior angle

So y = x/2 + x/2 which are marked as being opposite equal angles.

1/2 x + 1/2 x = x

y by substitution is = x /2 + x/2

y = x