2. A store owner paid $15 for a book. She marked up the price of the book by 60% to determine its selling price. What is the selling price of the book?

Use pythagorean’s theorem and find the missing side lengths of the two smaller triangles and add them together
13^2 - 12^2 = 5
15^2 - 12^2 = 9
5+9 = 14
14 is the length of each side of the square
14^2 + 14^2 = 19.8
19.8 is the diagonal length of the inside if the square

1/x-1+3/x-1=1
x is -1.333