Which of the following are equal to the expression? check all that apply

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?

Find the value of x for which abcd must be a parallelogram -9-6x x-30

Can someone me out here and the tell me the greatest common factor