college algebra
posted by karen on .
Lisa can shovel snow from her driveway in 50 min. Jim an do the same job in 55 min.How long would it take Lisa and Jim if they worked together?

lisa's rate = drive/50
Jim's rate = drive/55
combined rate = drive/50 + drive/55
= 21drive/550
so time = drive/(21drive/550) = 26 minutes