Jerry and his father are cleaning the house. Jerry can finish clean the house in 2 hours, his father can finish 0.5 hour faster than Jerry. How long would it take Jerry and his father to finish cleaning the house?

Answer 1

the father can do the job in 1.5 hours.
So, as with most of these work problems, if they can finish in x hours working together,
1/2 + 1/1.5 = 1/x
Now just solve for x.