Acceleration is directly related to what variable

Imagine a new pasture with grass growing on it. every day after the seeds have germinated, the number of blades of grass in the pasture triples. after 18 days, the entire pasture is completely covered in grass. how many days did it take for the pasture to be one-third covered in grass?

When only separate discreet points are graphed it is called?

Find the constant of variation for the relation and use it to write an equation for the statement. then solve the equation.