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daca ab+ac=84 si a=7 atunci 3b+3c-30 = ?

Răspuns :

ab+ac=84
a(b+c)=84
7(b+c)=84
b+c=84/7+b+c=12

3b+3c-30 =3(b+c)-30=3*12-30=36-30=6