If the length is twice the width, means length is : \(2\quad \times \quad 5\quad =\quad 10\)
To find the area multiply the width and length :\(10\quad \times \quad 5\quad =\quad 50\) . The air mattress' area is \(3\quad \times \quad 6\quad =\quad 18\) We should substract the air matress' field from the tent's : \(50\quad -\quad 18\quad =\quad 32\) The answer is 32 square feet.