A15.0 kg iron weightlifting plate has a volume of 1910 cm3 . what is the density of the iron plate in g/cm3?

Since the required units is gm/cm^3, first we will convert kg into grams.
15 kg = 15 x 1000 = 15000 grams of iron

Density can be calculated using the following rule:
density = mass / volume
Since both mass of volume are given, so we will just substitute in the equation to get the density.
density = 15000 / 1910 = 7.8534 gm/cm^3