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X + Y = 123 --> X – Y = 1 | X + Y = 23

X + Y = (X – Y) | (X + Y)

? + ? = 123 --> (X – Y) = 1 ir (X + Y) = 23

Kadangi:

X – Y = 1 ir X + Y = 23

Tai 2X = 24

24 / 2 = 12

12 – Y = 1

Y = 11

12 + 11 = 123