Question 177379
so Jack mows 1/4 of the lawn per hour and Mary mows 1/3 of the lawn per hour
:
together they mow

((1/4)+(1/3) of the lawn per hour
:
(3/12)+(4/12)=7/12 of the lawn per hour
:
(7/12)t=1(job)
:
{{{highlight(t=12/7)}}}hours