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a+b+c=198
b-c=123
atunci
2a+b+3c=?


Răspuns :

a+b-c+2c=198
a+123+2c=198
a+2c=75
a+2b=321
Adunam ultimele doua ecuatii:
2a+2b+2c=396
2a+b+3c+b-c=396
2a+b+3c=396-123
2a+b+3c=273