Question

stiind ca 2a+b+3c=123 , iar 2a+3b+c=77 calculati a+b+c

Answer 1

2a+b+3c=123
2a+3b+c=77   adunam cele trei relatii si rezulta
_____________
4a+4b+4c=200 /:4  acum impartim relatia la 4 => a+b+c=50

Answer 2

$2a+b+3c=123 \\ ------->(+) --> 4a+4b+4c=200|:4 =>a+b+c=50\\ 2a+3b+c=77$