A ladder leaning against a tree makes an isosceles right triangle with the tree and the ground. If the ladder is 10 feet long, how far up the tree does the ladder reach?

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?