From the information available, you cannot.
Well its quite easy: Density=Mass/Volume Volume=Mass/Density SO if mass and density of a cube are given you can easily find its volume.
You measure its mass and volume and then density = mass/volume.
LXWXH= volume find the mass and divide it with the volume mass divided by volume equals density
To find the mass of a cube by multiplying the density times the volume of the cube. The volume can be found by multiplying the height times the height times the length.
Use the formula:mass = volume x density
The simplest procedure is find the mass of the cube using a simple balance. Preciously measure the size hence volume of the cube. Then Density=Mass/Volume and unit is gm/cc
To find the density you need the mass and volume and then, density = mass/volume. Given a ruler, you can easily measure an edge of the cube. If that is x units, then the volume is x3 cubic units. However, it is not clear how you find a mass with just a balance. You need some standard weights, but these do not appear to be provided. You are stuck and cannot answer the question.
You need to find the mass and you need to find the volume. The latter may be calculated from the length of the side of the cube. Then, density = Mass/Volume in the appropriate measurement units.
To solve this you need to know the relationship that density = mass divided by volume We're given a length of a side of a cube as 2.5cm so to find the volume of the cube we need to cube it (length x bredth x height) volume = (2.5)3 = 15.625cm3 so if density = mass(136.95g)/volume(15.625cm3) density = 8.7648 g cm-3 in textbooks its given as (8.3- 8.7 gcm-3) as a typical density of brass.
Different metals have different densities, so to find the density either the type of metal or both the size and mass of the cube must be provided. Density is mass divided by volume.
mass = density x volume so volume = mass/density = 80/8.92 = 8.97 cubic centimeters; here density is g/cubic centimeter. Since it is a cube each side is cube root 8.97 = 2.08 centimeters
To measure the mass of a metal cube. First find it's volume, V = L (length) x W (width) x H (height), since it's a cube the L, W, and H are all the same so, V= L^3= H^3= V^3. Then you look up the density in a table or on the internet and multiple the density by volume to get mass. V = L (length) x W (width) x H (height) m = V * density (row)