{x=3+4y
{x^2-21y=28
{9+24y+16y^2-21y=28
{16y^2+3y -19=0
D=9-4*16*-19 =35^2
y=(-3+35)/32=1
y=(-3-35)/32=-38/32=-19/16
x=7
x=3-19/4= -7/4
{x=3+4y
{x^2-21y=28
{9+24y+16y^2-21y=28
{16y^2+3y -19=0
D=9-4*16*-19 =35^2
y=(-3+35)/32=1
y=(-3-35)/32=-38/32=-19/16
x=7
x=3-19/4= -7/4