[tex] \left \{ {{\frac{75a}{100}+\frac{90b}{100}=879 \atop {\frac{110a}{100}+\frac{120b}{100}=1246}} \right. \ \textless \ =\ \textgreater \ \left \{ {{75a+90b=87900} \atop {110a+120b=124600}} \right. \ \textless \ =\ \textgreater \
\left \{ {{5a+6b=5860} \atop {11a+12b=12460}} \right. \\
\left \{ {{10a+12b=11720} \atop {11a+12b=12460}} \right. \\
Le\ scadem:-a=-740=\ \textgreater \ a=740\\
7400+12b=11720\\
12b=4320=\ \textgreater \ b=360
[/tex]