Respuesta :
The first twin. The lucky numbers must be 2 and 1, respectively. The second twin is lying because 2+(1x2)= 4 not 5.
They are the liar. If 3x + 6y = 12, then x = 2 and y = 1. If x + 2y, then 2 + 2 would equal 4, not 5.