Respuesta :
Solution: Linndsey's 1 hour work [tex]=\frac{1}{3}[/tex]
Stephen's 1 hour work [tex]=\frac{1}{5}[/tex]
Linndsey's and Stephen's work together for 1 hour [tex]=\frac{1}{3} +\frac{1}{5} =\frac{8}{15}[/tex]
Therefore, the amount of work done in 1 hour by both Linndsey's and Stephen's is [tex]\frac{8}{15}[/tex]
Now the amount of Job left is [tex]1-\frac{8}{15}=\frac{7}{15}[/tex]
Let t be the amount of time Stephen takes to do the remaining job of [tex]\frac{7}{15}[/tex]
[tex]\therefore \frac{1}{5} \times t = \frac{7}{15}[/tex]
[tex]t=\frac{35}{15} =\frac{7}{3}[/tex] hours
Now let's convert hours into minutes as :
[tex]\frac{7}{3}\times 60 = 140[/tex] minutes
Therefore, it will take 140 minutes to Stephen to finish the job by himself.
