The area is equal to 230 CM.
area for rectangle :
area = width times length
area = 7 x 20 = 140CM
area for triangle:
area = 1/2 times base times height
area = 1/2 x 20 x 9 = 90CM
ADD:
140+90 = 230 CM
The diagonals of a rhombus bisect each other at right angles, therefore m∠BEC=90°
9z + 45 = 90
9z = 90 - 45
9z = 45
z = 45/9
z = 5