$(m_1g-m_2g)l/2=\bigg(m_1(l/2)^2+m_2(l/2)^2+\frac{ml^2}{12}\bigg) \alpha$

$3g\;l/2= \bigg[\large\frac{5l^2}{4}+\frac{2l^2}{4}+\frac{l^2}{12}\bigg]$

$3gl/2=\large\frac{22 l^2}{12}\alpha$

$\qquad\alpha=\large\frac{18g}{22l}$

$\qquad\alpha=\large\frac{9g}{11 l}$