In a given time of $10s,40$ electrons pass from right to left. In the same interval of time 40 protons also pass from left to right. Is the average current zero? If not, then find the value of average current.

No, the average current is not zero. Direction of current is the direction of motion of positive charge or in the opposite direction of motion of negative charge. So, both currents are from left to right and both currents will be added.

$$\begin{gathered} I_{zv}=I_{\text{electron }}+I_{\text{proton }} \\ =\frac{q_1}{t_1}+\frac{q_2}{t_2}=\frac{40e}{10}+\frac{40e}{10} \\ =8e \\ =8\times 1.6\times {10}^{-19}A \\ =1.28\times {10}^{-18}A \end{gathered}$$