Suppose that all work that has to be done is 1. Then:
- One crew can do this work in 10 hours. This means that they will do [tex]\dfrac{1}{10}[/tex] per hour.
- Another crew can do this work in 14 hours.This means that they will do [tex]\dfrac{1}{14}[/tex] per hour.
- Both crews together will do [tex]\dfrac{1}{10}+\dfrac{1}{14}=\dfrac{7+5}{70}=\dfrac{12}{70}=\dfrac{6}{35}[/tex] per hour.
If together they can do [tex]\dfrac{6}{35}[/tex] per hour, then for all work they will spend
[tex]\dfrac{1}{\dfrac{6}{35}}=\dfrac{35}{6}=5\dfrac{5}{6}[/tex] hours or 5 hours 50 minutes.
Answer: 5 hours 50 minutes.
