Sorry for so many questions

The rectangle at the top left has the perimeter of 24

The rectangle at the top  right has the perimeter of 42

The rectangle at the  bottom right has the perimeter of 32

So...we are trying to find the perimeter of the rectangle at the bottom left

Since the top rectangles are under the same height...call this height x

Call the width of the top left rectangle, y   and the width of the top/bottom right rectangles, z

Call the  height of the bottom left/right rectangles, w

So  

2x + 2y  = 24           2x + 2z =  42

x + y  = 12     (1)              x + z  = 21    (2)

Subtract (1) from (2)  and we have

 So    z - y = 9  ⇒   z  = y + 9    (3)

So...for the bottom right rectangle

2 ( w + z )  = 32

w + z  = 16

z = 16 - w      (4)

So...equate  (3)  and (4)

y + 9 =  16 - w

y + w  = 7

So  the perimeter of the bottom left rectangle  =

2 ( y + w)  =

2 (7)  =  14

Thank you so much