Murals by Max

     Maximillian Smith is a modern painter of murals. His preferred size of designs are those painted on large rectangles whose length-to-width ratio is 2-to-1.

     Two of his recent works of art have a unique mathematical connection with his daughter, Mindy, who became a for-real teenager just last year. You see, the numerical difference in the areas of these two paintings (as measured in square meters) is equal to Mindy's age.

     What is the sum of the two areas?