Write a problem that involves finding the unknown measure of a side of a rectangle include the solution?

Problem:
 The area of the patio of a relative's house is 20 square meters.
 The width of the patio is 2 meters.
 What is the length of the patio?
 Solution:
 The area is:
 A = (w) * (l)
 Where,
 w: width
 l: long
 Clearing l we have:
 l = A / w
 Substituting values:
 l = 20/2
 l = 10 meters

1/3÷4/9
=1/3×9/4
=3/4.