Solution :
Let $A$ 's work $=$ work of $l$
man
$\therefore \quad B^{\prime}$ s work $=1+20 \%$ of 1
$$
\begin{array}{l}
=1+\frac{20 \times 1}{100} \\
=\frac{6}{5} \text { men's work }
\end{array}
$$
Now, $\because$ Ram (l person) can do 1 work in 2 days
$\therefore$ Shyam i.e., $\frac{6}{5}$ (person) can do
1 work in $\frac{24}{\frac{6}{5}}$ days
$$
\begin{array}{l}
=\frac{24 \times 5}{6} \\
=20 \text { days; Ans. }
\end{array}
$$
Trick: Reqired days
$$
\begin{array}{l}
=\frac{100 \times 24}{100+20} \\
=20 \text { days; Ans. }
\end{array}
$$