A is thrice as good as workman as B and therefore is able to finish a job in 60 days less than B. Working together, they can do it in? A is thrice as good as workman as B and therefore is able to finish a job in 60 days less than B. Working together, they can do it in: A. 20 days B. 22 1/2 days C. 25 days D. 30 days How do we approach towards these kinds?

Let $v$ be the working speed of $B$. Then, the working speed of $A$ is $3v$. The working speed of $A$ and $B$ together is $4v$.

Now, the time $A$ spends is $t$ (in days), and the time $B$ spends is $t+60$.

Since the speed and the time are inversely proportional, their product is constant, so $3v\cdot t=v(t+60)$.

Can you continue?