Answer and Explanation:
Parallax method is used for finding the distance of objects in space there are two types of parallax method that is stellar parallax and trigonometric parallax.The disadvantage of using parallax method is that it can can not reach so far in the Galaxy due to this reason parallax method is generally not used for measuring distance in galaxy.
Answer:

Explanation:
Initial potential energy of the given spacecraft is given as

so we have

so we have






now total work done to move it to infinite is given
W = 0 - U

I got 35 lbs because your doubling the support