On a bar chart you can find the actual numbers on a pie chart it only gives you percentages.
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.
16. (x-5)(x+4) = x^2-x-20
17. 2x>7 = x=3.5
18. -4
63% decrease.
0.63•80=50.4kg
80kg-50.4kg=29.6kg