Answer:
density, mass of a unit volume of a material substance. The formula for density is d = M/V, where d is density, M is mass, and V is volume. Density is commonly expressed in units of grams per cubic centimetre.
Step-by-step explanation:
The rate of change is x2. So, since it's forty, it became 80 because 40x2=80!
Good luck for a good grade!