Answer
37 are girls.
Work Step by Step
$\frac{3}{4}\times36=\frac{3\times36}{4}=\frac{3\times9\times/\!\!4}{/\!\!4}=27$
If $\frac{2}{3}$ of the students on the second bus are boys, then $\frac{1}{3}$ are girls.
$\frac{1}{3}\times30=\frac{30}{3}=\frac{30\div3}{3\div3}=10$
$27+10=37$
