Answer: 45 pounds
Step-by-step explanation: To solve this word problem, let's set up a proportion. A proportion is just an equation that states two ratios are equal.
We know that 7 bags of empty aluminum cans weight 21 pounds so we can set up the ratio 7 bags/21 pounds. We want to find out how many pounds will 15 bags of empty aluminum cans weigh.
So using the same ratio of bags to pounds on the other side of the proportion, we have 15 bags/x pounds where x represents the number of pounds that 15 bags of empty aluminum cans will weigh.
Now, using cross products to find the missing value in this proportion, we have 4 times x which is 4x is equal to 21 times 15 or 315.
So we have 7x = 315.
Now to solve for x, we need to divide by 7 on both sides of the equation to get x = 45.
So, 15 bags of empty aluminum cans weigh 45 pounds
