Answer:
Given information: WY=ZX, A is the midpoint of WY and A is the midpoint of ZX.
To prove : WA =ZA
Proof:
A is the midpoint of WY, it means A divides WY in two equal parts.

So, WY is twice of WA.
.... (1)
A is the midpoint of ZX, it means A divides ZX in two equal parts.

So, ZX is twice of ZA.
... (2)
(Given)
Substitute the values from equation (1) and (2).

Divide both sides by 2.

Hence proved.