They rectangular courtyard has a cement walkway around its perimeter the dimensions of the courtyard are shown in the diagram. Write an expression in factored form that represents the areas of the cement walkway. Outside rectangle is 3 yards x 3 yards inside rectangle is(5x/1)yd and 21yd

Answer 1

3*3 - (5x/1)(21)
I suspect a typo. why have a denominator of 1?
and how can an inside rectangle have a length of 21 when the outside has a length of only 3?