Will and Mathew are building a 45 foot brick wall; if they work together they can complete the job in 25 hours. Working alone Will can complete the job in eight fewer hours than Mathew, how long would it take Will to complete the job working alone?

Solution:

Will:x hours

Mathew: x+8 hours

so 1/x +1/ (x+8) = 1/25

x= 46.3 hours

so  it take 46.3 hours for Will to complete the job working alone.