As we have seen that fraction means out of every one. Like $\frac{3}{4}\ of\ 12$ candies means $3$ out of $4$ parts of each candy. Since there are $12$ candies we have $\frac{3}{4} + \frac{3}{4} + \frac{3}{4}\ldots\ 12\ times$ which is equal to $\frac{3}{4} \times 12 = 9$.
Similarly $percent$ means $out\ of\ every\ hundred$. Percentage is represented using the symbol $\%$.
So, $10\%$ means $10\ out\ of\ every\ hundred$
When we represent $10\%$ as fraction we should get $\dfrac{10}{100} = \dfrac{1}{10}$
So, if you have $50$ candies, and you want to give $30\%$ of them to your friend. How many are you going to give?
Out of every $100$ candies you will give $30$ candies.
Out of every $1$ candy you will give $\dfrac{30}{100}$ candies.
Out of $50$ candies you will give $\dfrac{30}{100} \times 50 = 15$ candies.
Here are a couple of examples of how to solve percentage problems.
$\underline{Example\ 1:}$
You have $300$ pencils, and you give $40\%$ of them to your friend. How much are you left with?
Like in fraction $1$ is considered as whole, in percentage $100$ is considered as whole.
So if you gave away $40\%$ of what you have, you are left with $100-40 = 60\%$ of what you had.
Therefore you are left with $60\%\ of\ 300 = \dfrac{60}{100} \times 300 = 180$ pencils.
-----------book page break-----------
$\underline{Example\ 2:}$
$80\%$ of a number is $320$. What is the number?
$\dfrac{80}{100} \times\ Number = 320$
$\texttip{\therefore}{therefore} Number = 320 \times \dfrac{100}{80} = 400$