Which is the main gas that makes up the Earth's atmosphere?

Explanation:

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Explanation:

Earth's atmosphere is composed of about 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon, and 0.1 percent other gases. Trace amounts of carbon dioxide, methane, water vapor, and neon are some of the other gases that make up the remaining 0.1 percent

The total bill before the tip would be $ 25

Step-by-step explanation:

Let x be the amount of total bill,

∵ tip is 18% of the bill,

So, the amount of bill = 18% of x = 0.18x,

According to the question,

0.18x = 4.50

Hence, the total bill before the tip would be $ 25.