The equation for density is mass divided by volume i.e. #D = m/V#. The mass of the material is #5.6# #g#. The volume is #2.2# #mL#. If you're wondering why, it's because when you use a graduated cylinder and water to find the volume, you measure where the water is, then you put the object in, and measure it. You take the bigger number, and subtract it by the smaller number (which is taking the measurement with the object in the water, and subtracting the the measurement without the object).
Since the mass is #5.6# #g#, and the volume is #2.2# #mL#, you can divide #5.6# #g# by #2.2# #mL#. That gives you #2#.#bar54# #g#/#mL#. The unit is #g#/#mL# because you are taking grams and dividing it by milliliters.
#D = m/V#
Given: #m = 5.6# #g#, #V = 2.2# #ml#
#D = 5.6/2.2# = #2.545# #g#/#ml#
