A rectangular kitchen garden is 3 m longer than it is wide and has an area of 108 square metres. What is its width?

Explanation

1. 01

   Let the width be $w$ m; the length is $w + 3$ m. So $w(w + 3) = 108$.

2. 02

   $w^2 + 3w - 108 = 0$ factorises as $(w + 12)(w - 9) = 0$.

3. 03

   A width cannot be negative, so $w = 9$ m (length 12 m).