AS A PRESENT FOR MOTHER’S DAY, MARY WANTS TO DECORATE A 1-INCH-WID...

13. As a present for Mother’s Day, Mary wants to decorate a 1-inch-wide frame around a 6-inchby 9-inch photo of her mom. Mary paints each square inch with alternating striped and solidtriangles, as shown. How many striped triangles will Mary paint?