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. The point (0, 2) is the y-intercept of the line, so $\displaystyle{b}={2}\usepackage{cmbright}\Huge\$ . Since you move two units down and four units to the right to get to the point (4, 0), the slope is $\displaystyle\frac{{{r}{i}{s}{e}}}{{{r}{u}{n}}}=\frac{{-{2}}}{{4}}=-\frac{{1}}{{2}}\usepackage{cmbright}\Huge\$ .