3,000ml of an unknown liquid has a mass of 3 kg. What is its density?

The density, of a substance is its mass per unit volume. The symbol most often used for density is ρ, although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume: {\displaystyle \rho ={\frac {m}{V}}} where ρ is the density, m is the mass, and V is the volume.

the expression 15n + 2(3p) represents the amount isaiah spent buying gasoline and snacks, where n represents the price of each gallon of gasoline and p represents the cost of each snack that he bought. which statement is true about the amount isaiah spent?