Question 1162772
It takes Richard Semmler  4 hours to prepare a Little League baseball field.
In 1 hour Richard can do (1/4)th of the work.
It takes Larry Gilligan 7 hours to prepare the same field.
In 1 hour Larry can do (1/7)th of the work.
In 1 hour both combined can do (1/4+1/7)th of the field.
In 1 hour both can do (11/28)th of the field.
Therefore the field will be completed in (28/11) hours if both are working together.
Answer=2.5454 hours.