Two people push on opposite sides of a box with equal force. What happens to the box?

The box remains STATIONARY because the equal, opposite forces are BALANCED — the NET FORCE is zero. ASVAB Mechanical Comprehension tests force balance. When forces are balanced (equal and opposite), there is no net force, so there's no change in motion (Newton's first law — an object stays at rest). If one person pushed harder, there would be a net force and the box would accelerate toward the weaker side. Understanding balanced vs unbalanced forces and net force is commonly tested.