A 5.0 L volume of ideal neon gas (monatomic) is at a pressure of 3.0 atmospheres and a temperature of 450 K. The atomic mass of neon is 20.2 g/mol. What is the number of neon atoms in the gas?

Can you solve this problem for me in detail please? The equations needed /used are in College Physics that is available for free on course hero at the following link: College Physics (11th Edition) Solutions | Course Hero They are in chapter(s) 9 (rotational motion), 14 (Temperature and Heat) or 15 (Thermal Properties of Matter). I just can't figure out which ones to use to get the right answer and my assignment is due in 2 hours. Thank you.