The graph shows that 100 miles are traveled at 50 miles per hour. Using the equation for direct variation, $\displaystyle{y}={k}{x}\usepackage{cmbright}\Huge\$ , you get: $\displaystyle{100}={k}{\left({50}\right)}\usepackage{cmbright}\Huge\$ .

Solve for k to find $\displaystyle{k}={2}\usepackage{cmbright}\Huge\$ . Use this k value and $\displaystyle{x}={100}\usepackage{cmbright}\Huge\$ in a new equation for direct variation, and solve for y:

$\displaystyle{y}={2}{\left({100}\right)}\usepackage{cmbright}\Huge\$ or $\displaystyle{y}={200}\usepackage{cmbright}\Huge\$