john can finish the job in 5 hours. Steve can finish the same job in 4 hours. How many hours do they need to finish the jobs if they work together?

Question

beginning algebra

Answer 1

In an hour, John can finish 1/5th of the job whereas Steve can finish 1/4th of the job.

Together, in a hour they can finish 1/5 + 1/4 = 4/20 + 5/20 = 9/20th of the job.

If they can finish 9/20 of the work in an hour, then they will need 1/(9/20) = 20/9 hrs to finish it entirely. (~2.2 hrs )

I hope this helps

Answer 2

1/j + 1/s = 1/t

1/5 + 1/4 = 1/t

4t + 5t = 20

9t = 20

t = 20/9 = 2 2/9 hours working Together

t = 2.222.... hours