A lunar lander in powered descent at 100 m above the surface of the moon slows down from a velocity of 20 m/s to 0.5 m/s at constant acceleration. Assume that the lander has a mass of 20,000 kg and that burning the fuel does not change the mass. Answer the following questions:

How do I calculate the Thrust?

Please, all I need is to know what kind of equations I use for the question. I can do the rest.