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 may not have noticed the negative sign of the slope in the equation. The slope of the line is 1, not $\displaystyle-{1}\usepackage{cmbright}\Huge\$ .