How do you simplify $\left( {\dfrac{2}{5} + \dfrac{1}{5}} \right) - \dfrac{3}{{10}}$?

Hint: In this question, we want to calculate the given fraction. The fraction contains a numerator and a denominator. To solve the question, the first step is to remove brackets. For that, we must equal the denominator. To equal the denominator, we will take Least common multiple. Then, simplify by using addition and subtraction. Finally, we get the final value of the equation.

Complete step-by-step answer:
In this question, we want to find the value of
$ \Rightarrow \left( {\dfrac{2}{5} + \dfrac{1}{5}} \right) - \dfrac{3}{{10}}$
Let us take the least common multiple to remove the bracket.
$ \Rightarrow \left( {\dfrac{{2 + 1}}{5}} \right) - \dfrac{3}{{10}}$
Let us add the numerator of brackets.
 $ \Rightarrow \dfrac{3}{5} - \dfrac{3}{{10}}$
Again let us take the least common multiple. The LCM of 5 and 10 is 10.
$ \Rightarrow \dfrac{{6 - 3}}{{10}}$
Apply subtraction in the numerator.

$ \Rightarrow \dfrac{3}{{10}}$

Note:
Fraction: Fractions are the numerical values that are a part of the whole. If a number or a thing is divided into equal parts, then each part will be a fraction of the whole. A fraction is denoted as $\dfrac{a}{b}$. Where, ’a’ is the numerator and b is the denominator.
Steps to solve the fraction:
To add or subtract fractions, we have to check if the denominators are the same or different.
If the denominators have the same value then we can directly add or subtract the numerator by keeping the denominator common.
But if the denominators have different values, then we need to simplify by finding the least common multiple (LCM).
Least common factor (LCM): In arithmetic and number theory, the least common multiple, lowest common multiple, or smallest common multiple of two integers ‘a’ and ‘b’ is the smallest positive integer that is divisible by both ‘a’ and ‘b’. It is usually denoted by LCM(a, b).