a + b = 38
a + c = 40
b + c = 42
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(a + b ) + ( a + c) + ( b + c) = 38 + 40 + 42
2 x a + 2 x b + 2 x c = 120
2 x ( a + b + c ) = 120
a + b + c = 120 : 2
a + b + c = 60→ suma celor trei numere
60 - 38 = 22 (c) → al treilea numar
42 - 22 = 20 ( b) → al doilea numar
38 - 20 = 18 ( a) → primul numar
Verific: 18 + 20 + 22 = 60 → suma celor trei numere
Raspuns: 18, 20, 22