Answer:
540 square feet worth of paper
Explanation:
This is an area problem. Area is length multiplied by width. The provided length is 30 feet and the provided width is 18 feet. When they are multiplied, you get 540 square feet. Note that the height is the width in this context because if you laid the banner down, 18 would be the width. The banner is being held up, so the 18 feet is called the height.