The total weight of three pieces of windows is 24 lb. 12 oz. The first piece of window weighs the same as the second one while the last one weighs 10 lb. How much did the first piece of window weigh?

lb. oz.

Weight of the first piece of window: (24 lb. 12 oz. - 10 lb.) ÷ 2 = 14 lb. 12 oz.÷ 2 = 7 lb. 6 oz.