How do you write 3 3/5 as a percent?

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?

Rewrite the following without an exponent. (5/8)-1

The collection of beautiful oil paintings currently on display at an art gallery well defined; set not well defined; not a set