Question 70698
2x+y=3x-15
y=3x-2x-15
y=x-15 line formula
x+5=4y+2x
4y=x-2x+5
4y=-x+5 
y=-x/4+5/4 line formula
solution by graphing
{{{ graph( 300, 200, -6, 20, -20, 20, y = x -15, y = -x/4 +5/4) }}} (graph 300x200 pixels, x from -6 to 20, y from -20 to 20, of TWO functions y = x -15 and y = -x/4 +5/4). 
solution mathematically:
y=x-15 now substitute (x-15) for y in the other formula thus:
x-15=-x/5+5/4
x+x/5=5/4+15
6x/5=5/4+60/4
6x/5=65/4 now cross multiply
6x*4=65*5
24x=325
x=325/24
x=13.54 answer now substitute 13.54 for x & solve for y.
y=13.54-15
y=-1.46 answer.