Consider the line shown on the graph. Enter the equation of the line in the form \( y = m x + b \) where \( m \) is the slope and \( b \) is the \( y \) -intercept.
Joe earns \( \$ 9 \) per hour. He worked \( x \) hours on both Wednesday and Friday, and \( 8 \) hours on both Tuesday and Saturday. Write an expression to represent how much Joe earned.