Please help me (￣ ‘i ￣;)

100 points, hi, i’m not sure how to get the equation from the graph and table.

Fanny mendelssohn manages all the magazines and paperback books at a local grocery store. she prices many paperbacks to sell at $7.99. the cost to the store is $5.29. what is the markup rate on a paperback book, based on its cost?

Find the distance between the pair of points a(-1,8) and b(-8,4)