The idea here is that you need to use the mass of the empty cyinder and the mass of the cylinder with the liquid added to determine the mass of the liquid.
If the cylinder had a mass of 22.57 g when it was empty and a mass of 30.79 g after the liquid has been added, then it difference between these two values must be the mass of the liquid.
#m_"liquid" = m_"full" - m_"empty"#
#m_"liquid" = 30.79 - 22.57 = "8.22 g"#
Another important piece of information given to you is the volume of the liquid.
As you know, density is defined as mass per unit of volume. If you know what the mass of 1 mL of a substance is, then you know its density.
In your case, given that you've calculated the mass of the liquid to be 8.22 g and that you know its volume to be 7.25 mL, you can figure out its density by dividing the two
#rho = m_"liquid"/V_"liquid"#
#rho = "8.22 g"/"7.25 mL" = color(green)("1.13 g/mL")#