Two polarizer are oriented with transmission planes making an angle of 60 the percentage of incident unpolarized light that passes the system iz

Dear student,

Intensity of first transmitted light $I=\frac{I_0}{2}$

Angle between the plane is 60^o 

Intensity of the transmitted light from second Nicole is
 $$\begin{gathered} I\text{'}=\frac{I_0}{2}{\cos }^{2}60\circ \\ \frac{I\text{'}}{I}=\frac{1}{2}\times \frac{1}{2} \\ \frac{I\text{'}}{I}=0.25 \end{gathered}$$

The percentage of incident unpolarized light passing through the system is 
$$\begin{gathered} \frac{I\text{'}}{I}=0.25\times 100 \\ \frac{I\text{'}}{I}=25\% \end{gathered}$$

Regards.