If Sue can shovel snow from her driveway in 40 minutes Tom can do the same job in 55 minutes how long would it take sue and tom to shovel the drive way if they worked together?

Sue shovels (1/40th) of the driveway each minute.

Tom does (1/55th) of the same job each minute.

Together, they do (1/40 + 1/55) = (11/440 + 8/440) = (19/440) of the job each minute.

It would take them (440/19) = 23.16 minutes to do the whole job together. (rounded)