PLEASE SHOW YOUR WORK. Shawn designs a rectangular garden as shown below. He will design both rock sections to have the same width (x).

The area in, square feet, of Shawn’s garden is found be calculating 15(2x + 7). Shawn incorrectly says the area can also be found using the expression 30x + 7.

Describe the error in Shawn’s expression. As part of your explanation, find the difference, in square feet, between the actual area of Shawn’s garden and the area found using his expression.