The best answer to the question above would be the first choice, red supergiants, and supernovas. All of the elements that are heavier than oxygen are created by the fusion reactions in red supergiants and supernovas.
5 arrive - 3 leave = 2 left every minute
80 in total - 30 already there = 50 need to arrive
50/2
= 25 minutes
hope this helps :)
2. In the Soviet Union, what was a collective?
