X+y=105 и x:y=6 Решите пожалуйста эту систему

[latex] \left \{ {{x=105-y} \atop {(105-y):y=6}} \right. \ \textless \ =\ \textgreater \ \left \{ {{x=105-y} \atop {(105-y)=6*y}} \right.\ \textless \ =\ \textgreater \ \left \{ {{x=105-y} \atop {6y+y=105}} \right.\ \textless \ =\ \textgreater \ \left \{ {{x=105-y} \atop {7y=105}} \right. \\ \ \textless \ =\ \textgreater \ \left \{ {{x=105-y} \atop {y=15}} \right.\ \textless \ =\ \textgreater \ \left \{ {{x=90} \atop {y=15}} \right. [/latex]