Answer:
Nitrogen
Step-by-step explanation:
Nitrogen and oxygen are by far the most common; dry air is composed of about 78% nitrogen (N2) and about 21% oxygen (O2). Argon, carbon dioxide (CO2), and many other gases are also present in much lower amounts; each makes up less than 1% of the atmosphere's mixture of gases. Hope this helped!
-6 it is just the opposite of the number. So a positive would be a negative and a negative a positive. So the answer to your question is -6.
Answer
x - 15 = 18
Explanation
X is the variable that is required to get the answer 18
