What does Avogadro's law state and what is the formula​

Agas can holds 2.0 gal of gasoline. what is this quantity in cubic centimeters?

Ican determine the molar mass of an element by looking on the under the atomic mass for the element. for example the molar mass of phosphorus is 30.974 grams/mole. avogadro’s number tells me the amount of representative particles in 1 mole of any substance. this means 12.011 gram sample of carbon and a 32.0 gram sample of sulfur have the same number of atoms.

If anyone would be able to me out with these three questions it would be these are from the chem 2202 course.