Are aliens real in 2020

May someone explain how to do this question?

The summit of chimborazo, in ecuador, which is at a distance of about 6,384 km from the earth’s center. the bottom of the mariana trench, in the western pacific ocean, which is nearly 6,370 km from the center of the earth. on the surface of earth on the equator line.

What object a collides with object b and bounces back its final momentum is?