In the figure \displaystyle R1 is the air resistance.
Resolving up the plane
\displaystyle \begin{align} & F1+F-mg\sin {{30}^{\circ }}=0 \\ & \\ & F1=mg-F\sin {{30}^{\circ }}=60\times 9.81-\frac{1}{2}F \\ \end{align}
