Respuestas

2013-12-26T12:51:13+01:00
Sustración: x-y=d

 \left \{ {{x+y=400} \atop {x-y=x+80}} \right.

 \left \{ {{x+y=400} \atop {2x=480+x}} \right.

 \left \{ {{x+y=400} \atop {x=480}} \right.

 \left \{ {{y=400-480} \atop {x=480}} \right.

 \left \{ {{y=-80} \atop {x=480}} \right.

Los números son: -80 y 480.