Answer:
For
it will be plus or minus 
For
it will be plus or minus 
Step-by-step explanation:
Well for
it will be 5i
Because i = -1
Answer:
52min
Step-by-step explanation:
5 people..............5 walls............52 min
1 people...............5 walls...........52 x 5=260 min
1 people................20 walls.........260 x 4 =1040 min
20 people................20 walls........1040:20=52 min