How do you identify the percent of change as an increase or a decrease from 75 people to 25 people?

Hint: In this question, we have to find the percent of an increase or a decrease of the given statement. Thus, we will use the percentage formula to get the solution. We will use the formula $\left( \dfrac{N-O}{O}\times 100 \right)\%$ where N is the new value, O is the old value. Thus, in this problem, we know that the number of people decreases to 25 people. Thus, in this problem $N=25$ and $O=75$ . Therefore, we will put these values in the formula. After that, we will make the necessary calculations, to get the required solution for the problem.

Complete step by step solution:
According to the problem, we have to find the percentage of a given statement.
Thus, we will use the percentage formula to get the solution.
The statement given to us is 75 people to 25 people.
Thus, we will use the percentage formula $\left( \dfrac{N-O}{O}\times 100 \right)\%$ , where N is the new value and O is the old value --------- (1)
Thus, in this statement it is given that there are 75 people and it decreases to 25 people. Therefore, $N=25$ and $O=75$ , so we will put these vale in equation (1), we get
$\Rightarrow \left( \dfrac{25-75}{75}\times 100 \right)\%$
Now, we will subtract the numbers of the numerator in the above equation, we get
$\Rightarrow \left( \dfrac{-50}{75}\times 100 \right)\%$
On solving the numerator of the above term, we get
$\Rightarrow \dfrac{-5000}{75}\%$
On further simplify the above fractional term, we get
$\Rightarrow -66.7\%$

Therefore, the percent of change as an increase or a decrease 75 people to 25 people is equal to -66.7%, thus it is the decrease percent, which means there was a 66.7% decrease in the number of people.

Note: While solving this problem, do mention all the steps properly to avoid confusion. Do not forget to mention the percentage sign in all the steps and the negative sign. Always remember that percentage means when it is multiplied by 100.