IF you use the units, you can easily figure this out (as well as other , more comlicated equations)
density = 19.3 gm /cm^3 if you multiply this by volume 4.5 cm^3 the 'cm^3' cancels out and you are left with only grams as units
19.3 gm/ cm^3 * 4.5 cm^3 = 86.85 gm