The problem ask to calculate the slope of the line base on the diagram or table you give. To calculate the slope you must first know its formula and that is Rise/Run and also be Y/X so you must divide the Megabytes and the Minute and with that calculation the slope is 3.75 so the equation will be y=3.75x
Since the truck is 8 feet long then the longest log able to fit in the truck should be 8 feet as well. However talking reality, we might want to shorten it to make it fit better. Hope this helps!