We have three hundred students in total.
For every 3 boys, there are 2 girls. This can also be said as 1.5g = b
We can find the answer by setting up two equations.
g + b = 300
b = 1.5g
Then, when can use substitution method to put 1.5g in for b and we have g + 1.5g = 300
Solve for g to find girls and plug back in for boys