Density is a identity that says that for every 13.5g of lead (in this case) there is 1mL of lead.
So, in order to do this problem, you divide the 3.0g Pb by 13.5g Pb in order to get the volume.
3.0g Pb × [tex] \frac{1 ml Pb}{13.5g Pb} [/tex] ≈ .22mL Pb
