How was the first president in united states

if you meant "who" its George Washington

Explanation:

If you meant "how" George Washington (February 22, 1732 – December 14, 1799) was an American political leader, military general, statesman, and founding father who served as the first president of the United States from 1789 to 1797. Previously, he led Patriot forces to victory in the nation's War for Independence.He presided at the Constitutional Convention of 1787, which established the U.S. Constitution

oxygen = 21% of the atmosphere

nitrogen = 78%

carbon dioxide = 0.1%

argon =0.934%