Step 1 - Understanding the definition of density
Density is defined as the quotient between mass and volume. Basically, it measures how much volume is occupied by 1g of some substance. It is usually expressed in g/ml.
Defining it mathematically, we have:
Step 2 - Calculating the density
If we have the volume and the mass that occupies this volume, we can calculate the density already. The exercise says m=41.2g and v=50ml, therefore:
The density of this liquid is 0.82 g/ml.