Question

if action is always equal to the reaction explain how a horse can pull a cart​

Answer 1

It's the ground! The horse pushes backward on the ground, so the ground pushes forward with an equal force. If the horse can push back against the ground with a force greater than the cart's resisting force, then the horse will accelerate. is greater than another force pair

Answer 2

yes the horse cart can move because the gravitational pull is lesser than the force applied by the horse.