Find four consecutive integers with a sum of -66

The parabola opens: y=√x-4 (principal square root) up down right left

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?

How can you tell when x and y are not directly proportional?