Respuesta :

chichi202
(5z+8)(4z+20) multiply like terms like 5z & 4z as well as multiply eight and 20 witch equals 20z+ 160
So all around is 360 degrees. The sides directly in front of each other are congruent. 

(5z+8) + (4z+20) + (5z+8) + (4z+20) = 360
There is two of each one because of the congruent sides. 
Combine like terms. 
18z + 56 = 360
Get the variable by itself.
18z + 56 = 360
       -56      -56
18z=360
divide by 18

z = 20

Hope this helps! If you have any questions, just ask!