SOLUTION: Gertrude and Bertha are sisters. They are responsible for keeping the family's driveway clear of snow. If they work together they can complete shoveling in 30 minutes. One day Gert

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Question 708632: Gertrude and Bertha are sisters. They are responsible for keeping the family's driveway clear of snow. If they work together they can complete shoveling in 30 minutes. One day Gertrude had to do the job alone. It took her 40 minutes. How long would it have taken Bertha to shovel the same amount alone? You can assume that each girl always shovels at a constant speed.
Answer by josgarithmetic(39616) About Me  (Show Source):
You can put this solution on YOUR website!
r for rate
t for time in minutes
1 job is "shoveling the snow off the driveway".

Shoveler___________rate_________time____________jobs
Bertha______________r
Gertrude__________1/40
Both______________1/30

Usually one would try to fill in this whole table, but seeing enough information for expressions for rates, and knowing that their rates are additive, we have enough as shown.
r%2B1%2F40=1%2F30, find r, Bertha's rate.