in one minute, Lisa can shovel 1/35 of the driveway
in one minute, Tom can shovel 1/40 of the driveway.
in one minute, they both can shovel 1/35 + 1/40 = 8/280 + 7/280 = 15/280 = 3/56 of the driveway.
So, it will take them 18 2/3 minutes working together.
If b is the time for both,
1/b = 1/35 + 1/40
b = 35*40/(35+40) = 18 2/3
Lisa can shovel her drive way in 35 minutes. Tom can shovel the same drive way in 40 minutes. How long will it take them to do the job together?
1 answer
1 answer