You can put this solution on YOUR website!
Jack mows his lawn in six hours, Mary takes seven hours to mow the lawn.
If they work together how long would it take them?
Let t = time required if they both mow; (and each has a lawn mower)
Let the completed job = 1 (a mowed lawn)
multiply by 42, to clear the denominators, results:
7t + 6t = 42
13t = 42
t = 3.23 hrs, or 3 + .23(60) ~ 3 hrs 14 min
.54 + .46 = 1; confirms our solution of t = 3.23 hrs