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2x(a+3b)+3c=131 iar c+2b=19 ? pls

Răspuns :

c+2b=19 <=> 3c+6b=57
2x(a+3b)+3c=131 <=> 2a+6b+3c=131 <=> 2a+57=131 <=> 2a=74 <=> a=37

[tex]c+2b=19 \\ 2*(a+3b)+3c=131 \\ 2a+6b+3c=131 \\ 2a+3*(2b+c)=131 \\ 2a+3*19=131 \\ 2a+57=131 \\ 2a=131-57 \\ 2a=74 \\ a=\frac{74}{2} \\ a=37[/tex]