# How is density calculated?

You have a mass of $45.026$ $g$ that displaces a volume of $6.5$ $c {m}^{3}$. These units are guesses, you have not quoted any units when you set out the question.
So density, $\rho$ $=$ $\left(\text{mass")/("unit volume}\right)$ $=$ $\frac{45.026 \cdot g}{6.5 \cdot c {m}^{3}}$ $\cong$ $7.0$ $g \cdot c {m}^{- 3}$.