Lisa can shovel snow from her driveway in 45 minutes. Bill can do the same job in 65 minutes. How long would it take Lisa and Bill to shovel the driveway if they worked together?

Answer 1

Each minute, Lisa will shovel 1/45 of the driveway, while Bill will shovel 1/65 of the driveway.

Together, each minute they will shovel
(1/45+1/65) of the driveway.

They will take
1/(1/45+1/65) minutes to shovel the whole driveway.

Note: the answer is between 26 and 27 minutes.

Answer 2

2.5