The position of an object moving along a line is given by the function s(t) = - 18t + 108t. Find the average velocity of the object over the following intervals. (a) [1, 7] (b) [1, 6] (c) [1, 5] (d) [1, 1 + h] where h > 0 is any real number. (a) The average velocity of the object over the interval [1, 7] is (b) The average velocity of the object over the interval [1, 6] is (c) The average velocity of the object over the interval [1, 5] is (d) The average velocity of the object over the interval [1, 1 + h] is