Question

body weight 54 kg volume 20 dm of which material the body is made

Answer 1

Converting volume to $m^3$, obtain:

$$V = 20dm^3 = 20\times 10^{-3}m^3=0.02m^3$$

Thus, the density of the body is:

$$\rho = \dfrac{m}{V} = \dfrac{54kg}{0.02m^3} = 2700\dfrac{kg}{m^3}$$

Thus, the material might be aluminum.

Answer. Aluminum.