If the areas of △ CEF, △ Abe and △ ADF are 3, 4 and 5 respectively, the area of △ AEF can be obtained

If the areas of △ CEF, △ Abe and △ ADF are 3, 4 and 5 respectively, the area of △ AEF can be obtained

Let AB = a, ab = a, BC = B, and the area of \ \ \ \ \ \ \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\8