-7≤ r+3 ≤+7
-7-3 ≤ r ≤ 7-3
-10 ≤ r ≤ 4
Hrcku hdxvhjgf hgdchuh bbbbb logs. Job hrvh
Well I suppose it depends on how long you have in a day but...
with 30 people you can have it done in about 8hrs
but with 20 people you can have it done in about 12 hours
so my best guess would be anywhere between 20-30 people
See picture for solution steps and answer.