In a tug of war, when one team is pulling with a force of 85 N and the other 40 N, what is the net force?

Can someone explain to me how to do this problem ?

Aplane flies directly between two cities, a and b, which are separated by . from a to b, the plane flies into a headwind. on the return trip from b to a, the wind velocity is unchanged. the trip from b to a takes less than the trip from a to b. what is the airspeed of the plane, assuming it is the same in both directions

What is a good example of instantaneous speed