2x(3x8/2) + 2x((3+5)x5/2) =64
the trick is that the slop of triangle=3/8, but another shape slop is 2/5, these can not form a perfect big triangle with slop 5/13. so the big retangle has fake extra area 1. my english is not good hope you can understand it.
Dad’s email response to: http://i25.tinypic.com/dq5atu.jpg
