Question 163251
5x+4y=10
4y=-5x+10
y=-5x/4+10/4
y=-5x/4+2.5 (red line)
2x+y=1
y=-2x+1 (green line)
{{{ graph( 300, 200, -6, 5, -10, 10, -5x/4 +2.5, -2x +1) }}} (graph 300x200 pixels, x from -6 to 5, y from -10 to 10, of TWO functions -5x/4 +2.5 and -2x +1). 
Solution (-2,5)