First year ever in college physics and I am struggling.  Any help would be greatly appreciated . . . would love someone to please explain.

Air enclosed in a cylinder has density p=1.4 kg/m3

How do I determine the density of the air if the length of the cylinder is doubled while the radius is unchaged?

How do I determine what the density of the air if the radium of the cylinder is halved while the length is unchanged?