Final answer:
The soccer league should charge $0.30 for each juice box to cover the cost of the juice. It would cost $13.50 to purchase 45 boxes of juice.
Step-by-step explanation:
To cover the cost of the juice boxes, the soccer league should charge an amount that equals the cost of the boxes. They purchased 30 boxes for $9.00, so the cost of each box is $9.00 divided by 30, which is $0.30. Therefore, they should charge $0.30 for each juice box.
To calculate the cost of purchasing 45 boxes, we can use the cost of each box we found earlier. The cost of 45 boxes would be $0.30 multiplied by 45, which is $13.50. So, it would cost $13.50 to purchase 45 boxes of juice.