y = abc
a + b + c = 13
b + c = 10
a + c = 9
_____________
13 - 10 = 3 ( a)
9 - 3 = 6 ( c)
10 - 6 = 4 ( b)
y = abc = 346
x - y = y - z
x + z = y + y
x + z = 2 × y = 2× 346 = 692 → suma dintre x si z
y = 346
x + z = 692
x + y + z = ( x + z ) + y = 692 + 346 = 1 038 → suma numerelor
= 2 y + y = 3 y = 3 × 346 = 1 038