Technician a says that gears may be used to apply torque to other rotating parts. technician b says that gears may be used to multiply torque. who is right?

Both technicians are right.

Explanation:

Torque is defined as a rotational force that can be calculated by the formula T= F.d. Being F the force applied to a body to make it rotate and d the distance since the force is applied.  

So technician A is saying that gear can apply a torque to another gear, and that is true because it’s applying a rotational force to the gear next to it, in simple terms  -anytime I make something rotate, I'm generating a torque-. And for technician B, the torque also can vary as a function of the distance of the force applied (size of the gear), so, it can multiply the torque and change the rotation speed.

the total distance traveled by the car is

30km + 49km = 79 km .