Question 621419
Maria can shovel her driveway in 65 minutes.  Bill can do the same job in 40 minutes.  How long would it take Maria and Bill to shovel the driveway if they worked together?
.
Let x = time (minutes) it takes for both
then
x(1/65 + 1/40) = 1
multiply both sides by (65)(40):
x(40 + 65) = (65)(40)
x(105) = 2600
x = 2600/105
x = 24.76 minutes
or rounding:
x = 25 minutes