Question 132283
Sally is doing 1/4 each hour John 1/6 each hour so together they work 1/4 + 1/6 = 10/24 = 5/12 in a hour. 
5/12 -------> 1 hour
1 -------> x 
then x=12/5 so the response is 12/5 hours = 2.4 hours = 2 hours and 24 minutes