Let the portion of the job that Felix can complete in one hour=[tex]\frac{1}{x}[/tex]
Let the portion of the job that Max can complete in one hour= [tex]\frac{1}{3x}[/tex]
As, rate * time = portion of job done
We can simplify this like:
Portion that Felix can do in 9 hours + portion that Max can do in 9 hrs = 1 job done
[tex]\frac{1}{x}\times9+\frac{1}{3x}\times9=1[/tex]
[tex]\frac{9}{x}+\frac{9}{3x}=1[/tex]
[tex]\frac{9}{x}+\frac{3}{x}=1[/tex]
[tex]\frac{12}{x}=1[/tex]
[tex]x=12[/tex]
Hence, Felix can complete the whole job in 12 hours working alone.
Max can alone do the job in 3(12) = 36 hours.
