To find how many square feet her patch of lawn is, we need to find what the area of the lawn is. To find the area of a rectangle (which is what the patch of lawn is), we need to multiply length and width. The length of this rectangle is 10 feet and the width of this rectangle is 9 feet. To figure out what 10 * 9 is, we need to multiply all parts of 10 (10, and 0) by 9. 10 * 9 = 90, while 0 * 9 = 0. Adding them together, we get that the piece of lawn is 90 square feet.
