Two identical twins can only be distinguished by the characteristic that one always tells the truth and the other always lies. One twin tells you of a lucky number pair: "When I multiply my first lucky number by 3 and my second lucky number by 6, the addition of the resulting numbers produce a sum of 12. When I add my first lucky number and twice my second lucky number, the sum is 5." Which twin is talking? How do you know?

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.