Respuesta :
x-3*(-2x)=21
x+6x=21
7x=21
X=21/7
X=3
Now you substitute x=3 in the other equation
Y=-2*3
Y=-6
x+6x=21
7x=21
X=21/7
X=3
Now you substitute x=3 in the other equation
Y=-2*3
Y=-6