We know that the window is 864 square inches. To get this number in square feet, we must divide it by 12.
864/12 = 72
Therefore, the window is 72 square feet.
We also know that Reed uses 8 pieces of glass per square foot. To find the total number of pieces it will take him to make the window, we have to multiply the number of pieces it takes him to fill one square foot * the number of square feet.
72 * 8 = 576
Therefore, Reed will need 576 pieces of glass.
