4 books / 7.5 hours
4/7.5 = 0.533 book /hr
Almost one book for an hour.
Unit rate The rate for one unit of given quantity is called a unit rate. These unit rates are again considered as one quantity. Examples are km/h which is derived for instance given that the distance is 10km and the time to be there is 5 hours hence what is the velocity. Which is v=d/t henceafter, 2km/h. Another example is pressure which is force divided by the area. 1 N/m2 which is 5 N times 5 m2, the pressure is 1 N/m2