The slope-intercept form of a line is $\displaystyle{y}={m}{x}+{b}\usepackage{cmbright}\Huge\$ , where m is equal to the slope of the line and b is equal to the y-intercept. You made $\displaystyle-{6}\usepackage{cmbright}\Huge\$ the coefficient of y instead of the y-intercept in the equation.