Please help I have trouble answering these questions.

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?

What is the slope of the line shown below?

If g^-1(x) is the inverse of g (x) which statement must be true