Respuesta :

5 people , 1 wall ~ 20/5 = 4 minutes

1 person, 1 wall ~ 4/5 minutes

9 people, 1 wall ~ (4/5) x 9 = (36/5) minutes

Therefore 9 people, 9 walls ~ (36/5) x 9

= 64.8 minutes

= 1h 4 min 48 s

Answer:

It takes 20 minutes :)

Step-by-step explanation: