Electron is organizing the bookcase in the school library. He makes sure each shelf has 15 books on it. There are 9 shelves of math books and 6 shelves of science books.

Total amount of books in the bookcase =  225 books

Step-by-step explanation:

Each shelf is to have 15 books

Therefore total amount of books in the bookcase = {9×15} + {6×15} = 225 books

step-by-step explanation: h: (- 3, 6)

m: (1, - 2)

o: (7, 6)

r: (- 9, - 2)

midpoint of hm: (- 1, 2)

midpoint of or: (- 1, 2)

therefore, b is the midpoint of both diagonals bisect each other !

to prove the diagonals are perpendicular, show that the product of the slopes = - 1