Let A be the region between the lines y = 4x, x = 3 and y = 0. (Your answer to the following questions should be all integers.) a) What is the exact area of A? Area of A: b) What is the approximation of this area using three rectangles (of equal width) and right endpoints? Approximation using right endpoints: c) What is the approximation of this area using three rectangles (of equal width) and left endpoints?