(1) Write 2 rupees 5 paise and 2 rupees and 50 paise in decimals.
(2) Write 20 rupees 7 paise and 21 paise 75 paise in decimals.

Hint: In this question we are given two parts, which further have two parts in them. In all the four questions, we have to convert the rupee and paise into decimal. First, start by converting the paise into rupees as they can only be added if both the terms are in the same unit. After converting, simply add them to get the answer is decimals.

Formula used: $1{\text{ Rs}} = 100{\text{ paise}}$

Complete step-by-step answer:
(1) To add 2 rupees and 5 paise, we will first have to convert both the terms into one single unit. Since we have to convert it into decimals, we will convert 5 paise into rupees.
We know that $1{\text{ Rs}} = 100{\text{ paise}}$
\[ \Rightarrow 1\,{\text{paise}} = \dfrac{1}{{100}}{\text{ Rs}}\]
$ \Rightarrow 5{\text{ paise}} = \dfrac{5}{{100}}{\text{ Rs}}$
Now, since both the terms are in rupees, we can add them.
$ \Rightarrow 2 + \dfrac{5}{{100}} = 2 + 0.05 = 2.05{\text{ Rs}}$
Therefore, 2 rupees 5 paise in decimals \[ = 2.05{\text{ Rs}}\]
(ii) In this option also, we will convert both the terms into one unit.
We know that $1{\text{ Rs}} = 100{\text{ paise}}$
\[ \Rightarrow 1\,{\text{paise}} = \dfrac{1}{{100}}{\text{ Rs}}\]
\[ \Rightarrow 50{\text{ paise}} = \dfrac{{50}}{{100}}{\text{ Rs}}\]
Now, since both the terms are in rupees, we can add them.
$ \Rightarrow 2 + \dfrac{{50}}{{100}} = 2 + 0.50 = 2.50{\text{ Rs}}$
Therefore, 2 rupees 50 paise in decimals = $2.50Rs$
(2) We will start by converting both the terms into one unit.
We know that $1{\text{ Rs}} = 100{\text{ paise}}$
\[ \Rightarrow 1{\text{ paise}} = \dfrac{1}{{100}}{\text{ Rs}}\]
$ \Rightarrow 7{\text{ paise}} = \dfrac{7}{{100}}\;{\text{Rs}}$
Now, since both the terms are in rupees, we will add them.
\[ \Rightarrow 20 + \dfrac{7}{{100}} = 20 + 0.07 = 20.07{\text{ Rs}}\]
(ii) We will start by converting both the terms into one unit.
We know that $1{\text{ Rs}} = 100{\text{ paise}}$
\[ \Rightarrow 1{\text{ paise}} = \dfrac{1}{{100}}{\text{ Rs}}\]
\[ \Rightarrow 75{\text{ paise}} = \dfrac{{75}}{{100}}{\text{ Rs}}\]
Now, since both the terms are in rupees, we will add them.
$ \Rightarrow 21 + \dfrac{{75}}{{100}} = 21 + 0.75 = 21.75{\text{ Rs}}$

Note: It must be kept in mind that we cannot add a term in rupee with the term in paise as it will result in a wrong answer. In order to add two or more terms, the terms should always have the same unit.
For example: We cannot add 5m and 25cm.