The slope, 45, would be the amount he charges per hour; the y-intercept, 60, would be the fee he gets paid just for showing up.
Since 45 is multiplied by t, the amount of time, this shows us it is the cost per hour. Since that is the slope, the y-intercept must be 60. We know that y-intercepts are where the data intersects the y-axis; we also know they have an x (t, in this case) coordinate of 0. This means 0 hours have passed, which means it is an up front fee.
