I'm working with density, and the question asks to figure net mass. I'm not sure how I'm supposed to do that. Am I supposed to take the mass of the empty graduated cylinder and subtract that from the amount of mass in the graduated cylinder when filled with something? For example, the beginning mass is 25.419 and the ending mass is 34.210, therefore, the net mass would be 34.210 - 25.419 = 8.791. Is that the correct way to figure net mass?

That sounds about right - The gross mass being the mass of the container and substance. The net mass being the mass of just the substance. Presumably you work out the density by dividing your net mass over the volume of the liquid in the cylinder.