Question

An object is at rest on a table. The gravitational force is 10 N down, and the normal force is 10 N up. What is the net force?

Answer 1

--->  0 <---

suppose this "0" is an arbitary object. The net force will be against it from both sides (left and right)

Answer 2

N + G = F(net)

N=+10 N, G=-10 N;

So, +10+(-10)=0

Answer is F(net) = 0 N.