Answer:
Refer below.
Explanation:
To solve Mary's query about calculating the density of objects, the essential concept to understand is that density is calculated by dividing an object's mass by its volume. Thus, the sentence should be completed with the word "dividing," making the full statement:
She can calculate the density of the small rock by dividing its mass by its volume.
[tex]\boxed{ \begin{array}{ccc} \text{\underline{Density Formula:}} \\\\ \rho = \dfrac{m}{V} \\\\ \text{Where:} \\ \bullet \ \rho \ \text{is the density} \\ \bullet \ m \ \text{is the mass} \\ \bullet \ V \ \text{is the volume} \end{array} }[/tex]