How do i graph the following X=4

Mrs. renoir has completed the interior portion of a quilt top measuring

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?

Aboat costs 19200 and decreases in value by 12% per year. how much will it cost in 5 years