The length of a rectangular garden is 4 yd greater than the width. The area of the garden is 96yd 2. Find the length and width?

You can solve a quadratic equation for the dimensions.
  (x+4)*x = 96
It is often quicker to look at the factors of the area number to see if any meet the requirements.
  96 = 1*96 = 2*48 = 3*32 = 4*24 = 6*16 = 8*12
The factors 8 and 12 differ by 4, so we conclude the garden is 12 yd by 8 yd.