On the "Number of Trips" data sheet, use the High-low method to determine the cost equation that expresses how monthly operating costs behave in relation to the number of trips made. First, highlight the two months you will be using (the highlight icon looks like a spilling paint bucket). Follow directions on the screen to calculate the variable and fixed portions of the equation in the space provided. Then use "insert textbox" to state the resulting high-low equation and define the x and y variables in the equation (x = ?; y = ?).