a= o fusta
b= o rochie
[tex] \left \{ {{5a+3b=14,1} \atop {4a+9b=29,1}} \right. =\ \textgreater \ \left \{ {{5a+3b=14,1 / ori(-3)} \atop {4a+9b=29,1}} \right. (+) =\ \textgreater \ \left \{ {{-15a-3b=42,1} \atop {4a+9b=29,1}} \right. (+) =\ \textgreater \
\\ =\ \textgreater \ -11a=13,2 =\ \textgreater \ a = 1,2 material =\ \textgreater \ 6+3b=14,1 =\ \textgreater \
\\ b=8.1 material [/tex]