The earth's radius is 6400 km. A 25-kg mass is taken 201 km above the earth's surface. What is the object's mass at this height?

Mass will not change at any place.

Only weight changes to to gravity. so answer-25KG.\ Mass is not the same as weight, even though we often calculate an object's mass by measuring its weight with a spring scale, rather than comparing it directly with known masses. An object on the Moon would weigh less than it does on Earth because of the lower gravity, but it would still have the same mass. This is because weight is a force, while mass is the property that (along with gravity) determines the strength of this force. from wikipedia.