times first equation by 100
7x+9y=400000
multiply second equation by -7
-7x-7y=-2829.4
add to other equation
7x+9y=400000
-7x-7y=2829.4 +
0x+2y=397170.6
2y=397170.6
divide by 2
y=198585.3
sub back
x+y=404.2
x+198585.3=404.2
minus 198585.3 both sides
x=-198181.1
(-198181.1, 198585.3)
