A gardener plans to extend the length of a rectangular garden by 7 feet. Let x represent the garden's original length. The expression 8(x + 7) represents the area of the garden,
where 8 is the width, in feet, and (x + 7) represents the extended length, in feet, of the garden. When
asked for the area of the extended portion, the gardener incorrectly said it was 15 square feet.
Expand the expression to find the area of the extension. Then describe an error the gardener might
have made.