Net charge of system with one + 6e sphere and another - 4e sphere.

Answer: + 2 e

Explanation: Net charge of a system is sum of charges on all the constituents of the system.

The system contains two spheres. Charge on one sphere is:

q₁ = + 6 e

Charge on the second sphere is:

q₂ = - 4 e

Net charge of the system is:

q = q₁ + q₂

q = + 6 e + (-4 e) = + 2 e

Thus, the net charge of system is + 2 e.