Answer:
Sediments are used to provide the proxies to understand the environmental changes as, the sediments are formed by the activity of the weathering from the wind, glacier and the water. The different weathering agent and other transportation agent are different types of the mark over the sediments that help in the study of the past environment.
The earth's distance from space is 0 because it is in space
The answer should be 3a-6+14 = 3a+8.