\left \{ {{\frac{x}{y}=0,6} \atop {x+y=1000}} \right.
\left \{ {{x=0,6y} \atop {0,6y+y=1000}} \right.
\left \{ {{x=0,6y} \atop {1,6y=1000}} \right.
\left \{ {{x=0,6y} \atop {y=625}} \right.
\left \{ {{x=0,6*625} \atop {y=625}} \right.
\left \{ {{x=375} \atop {y=625}} \right.
\frac{375}{625}=0,6