Lindsey and Stephen work at a factory. Lindsey can complete one full job in three hours, and Stephen can complete the same job in five hours. If Lindsey and Stephen work together on the job for one hour, then how long, in minutes, will it take Stephen to finish the job himself?

Answer 1

L --- 1/3 job/hr
S ---1/5 job/hr

together 1/3 + 1/5 = 8/15 job/hr

(8/15 j/h)(1 h) = 8/15 job done
that leaves (15-8)/15 = 7/15 to do

(1/5)job/hr * t = 7/15 job

t = 35/15 hr for S to finish

35/15 hr * 60 min/hr = 140 min