A) CD = Perimeter - the rest of the length
= (20x - 3) - (2x + 6) - (4x+3) - (5x-3)
= 9x - 9 cm//

B) AD = BC
hence 2x + 6 = 5x - 3
3x = 9
x = 3cm

:. perimeter
= 20(3) - 3
= 57cm //

C) to find area of trapezium,
We need 2 parallel lengths & perpendicular breadth.
In other words, we need to find AX OR BY

Focusing on AX:
(1) We will find DX first
DC = AB + DX + CY
= AB + 2 DX
from (a):
9x - 9 = 4x + 3 + 2DX
Since x = 3:
27 - 9 = 12 + 3 + 2DX
DX = 1.5cm

Since DX = 1.5cm, AD = 12cm,
By Pythagoras theorem:
AX = square root (12^2 - 1.5^2)
= 11.906cm

:. Area of trapezium
= 0.5 * 11.906 * (AB + CD)
= 0.5 * 11.906 * 33
= 196cm^2 (3sf) //