Carl can wash all the windows of his house in 7 hours. His wife Maggie can wash all the windows in 4 hours. How many hours will it take for both of them working together to wash all the windows? Choose the most appropriate option:	A) 2	B) 2 1/4	C) 11 6/2	D) 4 1/2	E) 5
Work hrs=AB/(A+B)= 28/11 =11 6/2   Answer is 11 6/2
<result>C</result>
Carl can wash all the windows of his house in 7 hours. His wife Maggie can wash all the windows in 4 hours. How many hours will it take for both of them working together to wash all the windows?