76% of the students in a school are boys. If the number of girls is 204, then the total number of students is :

Let the total number of students be x
Then,
$$\eqalign{ & \left( {100 - 76} \right)\% {\text{ of }}x = 204 \cr & \Rightarrow 24\% {\text{ of }}x = 204 \cr & \Rightarrow \frac{{24}}{{100}}x = 204 \cr & \Rightarrow x = \left( {\frac{{204 \times 100}}{{24}}} \right) \cr & \Rightarrow x = 850 \cr} $$