For every force an object applies, there is an equal and opposite force acting on the object. Summarize these two principles as one.

will give brainliest

Thats newtons third law of motion

Explanation:

Which states at any force there's an equal and opposite reaction which means that always forces work in pairs

And that's according to my understanding fella

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.