Question 151239
y = 1/7x -20 (RED LINE)
y = 7x + 15 (GREEN LINE)
{{{ graph( 300, 200, -6, 5, -20, 22, x/7 -20, 7x+15) }}} (graph 300x200 pixels, x from -6 to 5, y from -20 to 22, of TWO functions x/7 -20 and 7x +15). 
intersection=(-5.104,-20.728)