Answer :
combined work problems
job/time + job/time = job/ total time
(1/80) + (1/100) = 1/T
(10/800) + (8/800) = 1/T
18/800 = 1/T
800/18 = T
44.44 hrs = T
job/time + job/time = job/ total time
(1/80) + (1/100) = 1/T
(10/800) + (8/800) = 1/T
18/800 = 1/T
800/18 = T
44.44 hrs = T