Either you can practice your visualisation until you can recognise it intuitively (Which takes a fair amount of practice! 🙂 or else you will have to think of quick ways to prove it on the spot (for example the height of the trapezia will be the same as it is midpoint, the angles will be the same as all are 60 and 120, so can easily show congruence)
CAT-holics 
B 1/2
option (1) – 1/3
1/2 B
By visualisation method :
3/6= 1/2
How to prove by symmetry arguments that areas on both sides of creeze are same. We cant take on the face of it.
Either you can practice your visualisation until you can recognise it intuitively (Which takes a fair amount of practice! 🙂 or else you will have to think of quick ways to prove it on the spot (for example the height of the trapezia will be the same as it is midpoint, the angles will be the same as all are 60 and 120, so can easily show congruence)
regards
J