Solve the system of equation
2x+4y=20
2x+8y=4

I cant remember this would be substitution, correct? If so,
2x+8y=4
-2x      -2x

      8y=4-2x
     
       8    8  8

y=1/2-1/4x

substitute this into 2x+4y=20

2x+4(1/2-1/4x)=20
2x+2-x=20
     -2      -2
        
   2x-x=18
   1x=18

x=18

substitute x in the equation

2(18)+8y=4
  36 + 8y=4
  -36        -36
    
        8y=-32
        
         8      8

y= -4
x= 18