Explain simply why 280 is the correct answer to: Tom fills a 250 pound sandbag 80% full. But the filling material he is using is 40% heavier than sand. How much does the bag weigh?. Explanation:
The bag full of sand would weigh 250 * .8 = 200 pounds. The filling material would make it 200 * .4 = 80 pounds heavier. So it weighs 200 + 80 = 280 pounds.