Density is defined as the mass per unit volume.
formula is as follows

we have been given the density and volume so we need to find the mass of ethylene glycol
if we rearrange the equation making mass the subject
mass = density x volume
density = 1.11 g/cm³
this means that 1 cm³ of solution has a mass of 1.11 g
since mL = cm³
therefore 387 cm³ of solution has a mass of 1.11 g/cm³ x 387 cm³ = 429.6 g
mass of ethylene glycol is 429.6 g