Question 92409
y=2x-1 (red line) this line has a slope (m=2)
y=-x+2 (green line) this line has a slope (m=-1)
{{{ graph( 300, 200, -6, 5, -10, 10, y = 2x -1, y = -x +2) }}} (graph 300x200 pixels, x from -6 to 5, y from -10 to 10, y = 2x -1 and y = -x +2). 

INTERSECTING STREIGHT LINES ARE FORMED.
COMPARE THE SLOPES -- ONE IS POSITIVE & THE OTHER IS NEGATIVE.