6x+y=4
X-4y=19
You are going to want to take -4y and put it to the other side:
X-4y=19
Which is: x=4y+19
6x+y=4
Now substitute x !
6(4y+19)+y=4
Distribute it
24y+114+y=4
Now combine like terms
25y+114=4
Subtract 114 both sides
25y= -110
Y=-4.4
Now you have y so take either equation and substitute the y
X-4(1.4)=19
X+17.6=19
X=1.4
Y=-4.4