Question

Iron has a density of 7.86 g/cm3. calculate the volume (in dl) of a piece of iron having a mass of 3.72 kg

Answer 1

Density is the mass divided by the volume of the object

$\rho = \frac{m}{V}$

you know denisty and you know mass so you can determine volume if you rearrange the formula

$V= \frac{m}{\rho}$

however, when you're doing the division, make sure the units match, since density is given in grams and mass  is given in kilograms

once you have volume in cm3, convert that into "dl"