Ответ :

[tex] \left \{ {{3x+4y=230} \atop {y=5x}} \right. \left \{ {{3x+4*5x=230} \atop {y=5x}} \right. \left \{ {{23x=230; x=10} \atop {y=50}} \right. [/tex]
Ответ :(10;50)