Figure P30.31 is a cross-sectional view of a coaxial cable: The center conductor is surrounded by a rubber layer, an outer conductor, and another rubber layer. In a particular application, the current in the inner conductor is 1.00 A out of the page, and the current in the outer conductor is 3.00 A into the page. Assuming the distance is 1.00 mm, determine the magnitude and direction of the magnetic field at (a) point a and (b) point WC.