Plz help

Let the total amount of students in the class be $s$. 

Note that ${5 \over 9}$th of the students will get 4 sweets, ${1 \over 3} \times (1 -{5 \over 9}) = {4 \over 27}$th of the students will get 3 sweets, and ${8 \over 27}$th of the students will get 2 sweets. 

From this, we can form the equation: $({5 \over 9}s \times 4) + ({4 \over 27}s \times 3) + ({8 \over 27}s \times 2) = 264$. 

Simplifying, we get: ${88 \over 27}s = 264$, meaning there were originally $\color{brown}\boxed{81}$ students.