Finding the Rate of change over the time Intervals

Consider the fuction as representing the value of an ounce of silver in Indian rupees as a function of the time t in days. Find the average rates of chage of R(t) over the time intervals [t, t+h], where t is as indicated and h = 1, 0.1, and 0.01 days. Hence, estimated the instantaneous rate of change of R at time t.