Answer: [tex]1\frac{7}{8}\ hours[/tex]
Step-by-step explanation:
If they are working alone
Jim does of the job in 1 hour=[tex]\frac{1}{3}[/tex] of work
John does of the job in 1 hour=[tex]\frac{1}{5}[/tex] of work
Let x be the number of hours to do the job if they work together.
Thus, each hour, they do [tex]\frac{1}{x}[/tex] of the job when they work together.
According to the question,
[tex]\frac{1}{x}=\frac{1}{3}+\frac{1}{5}[/tex]
[tex]\Rightarrow\frac{1}{x}=\frac{5+3}{15}\\\Rightarrow\frac{1}{x}=\frac{8}{15}\\\Rightarrow\ x=\frac{15}{8}=1\frac{7}{8}\ hours[/tex]
∴ The number of hours to do the job if they work together= [tex]1\frac{7}{8}\ hours[/tex]
