Slope intercept form is y=mx+b, where x is the x-intercept, m is the slope, and b shifts the entire line up or down the graph.
$20 per hour would be the slope, where m is 20 and x is "hour"
y = 20x + b
b is the $12 for life jackets, as it's an added cost.
y = 20x + 12
To calculate your total cost (y), you'll put the number of hours (x) that the boat is rented into the equation, and solve for y.
So, the slope-intercept form to find the total cost is
y = 20x + 12
