Hint: Use Gauss' law.
Step 1: Find the net charge inside the closed surface.
From Gauss' law, the electric flux through an enclosed surface is given by, .
Here q is the net charge inside that enclosed surface.
Step 2: Find the flux through the surface.
Now, the net charge on a dipole is givon by, -q + q = 0
The electric flux through a surface enclosing a dipole
