Math
posted by Linda on .
Mike can complete a project in 60 minutes͵ and if Mike and Walter both work on the project͵ they can complete it in 40 minutes. How long will it take Walter to complete the project by himself?

Mike (1/60) project/min
Walter (w project/min)
together
(1 + 60 w)/60 project /min
[(1+60 w)/60 ] 40 = 1 project
1 + 60 w = 6/4
60 w = .5
w = .0083333
1/w = min/project = 120 minutes