please solve these problems

Consider the following cost function. a. Find the average cost and marginal cost functions. b. Determine the average and marginal cost when x = a. c. Interpret the values obtained in part (b). C(x) - 0.04x + 0.8x-+ 40x + 90, Osxs 1500, a = 800\fThe graph of s = f(t) represents the position of an object moving along a line at time t2 0. AS a. Assume the velocity of the object is 0 when t= 0. For what other values of t is the velocity of the object zero? b. When is the object moving in the positive direction and when is it moving in the negative direction? c. Sketch a graph of the velocity function. d. On what intervals is the speed increasing? 2An object is dropped from a tower, 400 ft above the ground. The object's height above ground t seconds after the fall is s(t) = 400 - 161". Determine the velocity and acceleration of the object the moment it reaches the ground. The velocity of the object the moment it reaches the ground is |fu/s. (Simplify your answer.)