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Daca a+b=12 si b+c=9
2a+6b+4c = ?​


Răspuns :

Răspuns:

a+b=12 I·2 => 2a+2b=24

b+c=9 I·4 => 4b+4c=36

2a+2b+4b+4c=24+36

2a+6b+4c=60

a+b=12
2a+2b=12x2
2a+2b=24
b+c=9
4b+4c=9x4
4b+4c=36
2a+2b=24
4b+4c=36
24+36=60