The slope of an absolute function at the point where it evaluates to zero is undefined.
Here, when x=1, so |4x-4|=|4-4|=|0|, the slope is undefined. This is where the vertex of the "V" on the graph of the absolute value function.
I think it is 4.5 miles per hour
75/60 = 15/12 = 5/4. This is the lowest term
