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a plus b egal 129 a minus b egal 41

Răspuns :

{a+b=129
{a-b=41
2a=170
a=170:2=85
85+b=129
b=129-85=44
a+b=129
a-b=41
a=b+41
2b+41=129
2b=129-41=88
b=88:2=44
a=44+41=85

Proba:
85+44=129
85-44=41