Question

[dashingtiger]

AD = 18, AB = 15, all 6 squares are equal. what is the area of the shaded space?

1. is it true that the two white spaces outside of the squares on the right are congruent and add up to two squares? I cut out the paper and they seem fit but I don't know how to prove it
2. It feels like the shaded area is equal to the top left white plus the top right white, again, I don't know how to proof it
3. finally, am I thinking this all wrong? should I connect the cross points that land on the edges instead ?