Help with Avogadro's Law of Combining Volumes, such as determining volume at STP

[Kathleen]

and SATP, etc.? Please help me! I don't understand how to do these problems:

Standard Temperature & Pressure:
22.4 L at 0oC and 1 atmosphere pressure

Standard Ambient Temperature & Pressure:
24.8 L at 20oC and 1 atmosphere pressure


A sample of carbon dioxide gas has a volume of 55.0 mL at 45oC and 85.0 kPa. Determine the volume at STP and SATP.

What pressure will 37.18 grams of CO2 gas exert on a container at standard temperature?

Find the mass of 543 mL of acetylene gas, C2H2, collected at a pressure of 85.0 kPa and standard temperature.

What is the density of CO2 gas measured at 5oC and 200 kPa?

you don't need to tell me the answer, but please provide me with steps on how to solve those problems. i'm dying here.