Do Action and Reaction
Forces Cancel?

Since action and reaction forces are equal and opposite, why don't they cancel to zero?

First the orange has its own system, and does not accelerate. The apple pulling on it is an external force meaning the action and reaction forces do not cancel because the force is not part of the system but if the apple and the orange are one system then the action and reaction forces would cancel out and would need and external force to cause it to accelerate external meaning outside both the apple and the orange.