Present price of a machine is Rs. $2p$ and if the price of the machine decreases by $2r\%$ in each year, the price of the machine after $2n$ years will be:

The formula for the value of an asset after uniform depreciation over time is given by:
$$A=P{\left(1-\frac{R}{100}\right)}^T$$

Where:

* Initial value ($P$) = $2p$
* Annual depreciation rate ($R$) = $2r\%$
* Time period ($T$) = $2n$ years

Substituting these values into the depreciation formula:

$$A=2p{\left(1-\frac{2r}{100}\right)}^{2n}$$

Simplifying the fraction inside the parentheses:

$$A=2p{\left(1-\frac{r}{50}\right)}^{2n}$$