Answer:
D. 4z + 20
Step-by-step explanation:
side length of the square : ( z + 5 )
[tex] {z}^{2} + 10z + 25 \\ {z}^{2} + 5z + 5z + 25 \\ z(z + 5) + 5(z + 5) \\ (z + 5)(z + 5) \\ [/tex]
perimeter of the square :
[tex](z + 5) \times 4 \\ 4z + 20 \\ [/tex]
