Three people can do 1/8th of the job in 1 hour. Then 1 person can do 1/24th of the job in 1 hour. Then 2 people can do 1/12th of the job in 1 hour. Then 2 people can do the whole job in 12 hours.
John
Egw to Beta kai to Sigma
My calculator said it, I believe it, that settles it