The salary of Anup is $30\%$ more than that of Barun. By what percentage is the salary of Barun less than that of Anup?

Let the salary of Barun be $\text{Rs. }100$.
Since Anup's salary is $30\%$ more, Anup's salary $=100+30=\text{Rs. }130$.

The amount by which Barun's salary is less than Anup's $=130-100=30$.
Percentage less relative to Anup's salary:

$$\text{Percentage Less}=\frac{30}{130}\times 100=\frac{300}{13}\approx 23.076\%\approx 23.07\%$$