Maria can cut a lawn and trim the hedges in 8 hours. Debbie can do the lawn and hedges in 6 hours. When Maria, Debbie, and Bill worked together it took 2 hours

Question

Please give process. Thanks!

Answer 1

1/8 = portion of the job done by Maria per hour

 

1/6 = portion done by Debbie per hour

 

1/2 = portion done per hour if Maria, Debbie, and Bill work together

 

Let x = time (in hours) that it takes Bill to do the job alone

 

1/x = portion of Job done by Bill per hour

Then, 1/8 + 1/6 + 1/x = 1/2

 

Multiply by the LCD, 24x:  3x + 4x + 24 = 12x

 

                                                      5x = 24     x = 4.8 hours