Jim is rearranging his apartment and needs to move his entertainment center. If the gravity exerts 15 N and there is 10 N of friction, how much force will Jim need to exert to move it?

Assuming he pushes parallel to the ground, he will only need to exert 10N of force to overcome the friction. The 15N of gravity only acts downward and since the furniture only moves horizontally this force plays no part.