Line [math]a[/math] and Line [math]c[/math] are parallel lines. They have the same slope. Move line [math]a[/math] be moving slider [math]m[/math] or [math]b[/math]. The slope for line [math]a[/math] stays the same as line [math]c[/math]'s. [math]y=mx+b[/math] is the slope-intercept form of a linear equation. The slope is [math]m[/math]. Move slider [math]m[/math]. The slope for both lines will change. Move slider [math]b[/math]. Line [math]a[/math] will move, but line [math]c[/math] will be stationary.