Perimeter of ABCD:
= 2(4x) + 2(3x+4)
= 8x + 6x + 8
= 14x + 8
Perimeter of EFGH:
= 5x + 5x + x - 3 + 7x - 3
= 18x - 6
Perimeter of both shapes are the same
14x + 8 = 18x - 6
-4x = - 14
x = 7/2
x = 3.5
So
The width of rectangle = 3x + 4 = 3(3.5) + 4 = 14.5 cm
The length of rectangle = 4x = 4(3.5) = 14 cm
Area of rectangle = 14.5 x 14 = 203 cm^2
Answer
Area of rectangle = 203 cm^2