Explanation

Given fractions are \large\frac{3}{5}\normalsize,2\large\frac{1}{10} or \large\frac{21}{10}, \large\frac{6}{25}
The formula we use to get the HCF of two or more fractions is:

\large\frac{The\ HCF\ of\ Numerator}{The\ LCM\ of\ Denominator}

Here, given numerators are 3,21 and 6.
\therefore The HCF of 3,21 and 6 is =3
And given denominators are 5,10 and 25.
\therefore The LCM of 5,10 and 25 are =50
So that, the HCF of \large\frac{3}{5}\normalsize,2\large\frac{1}{10} and \large\frac{6}{25} is =\large\frac{3}{50}
Ans: HCF is \large\frac{3}{50}.