The equation given in A is the point slope form of the given line, so this equation does represent the line. However, the equation given in B represents the line, too. When $\displaystyle{x}={2}\usepackage{cmbright}\Huge\$ and $\displaystyle{y}={4},{y}-{2}={4}-{2}={2}\usepackage{cmbright}\Huge\$ and $\displaystyle-{\left({x}-{4}\right)}=-{\left({2}-{4}\right)}=-{\left(-{2}\right)}={2},\usepackage{cmbright}\Huge\$ so the line given in B has the correct slope and goes through the point (2, 4).