VeryImportant please

The figure below shows a long conducting coaxial cable and gives its radii (R1 = 3.54cm, R2=7cm, R3=16cm). The inner cable has a uniform current density of J = 7.2 A/m2, and the outer cable carries a uniform current I = 4.3A flowing in opposite direction. Assume that the currents in each wire is uniformly distributed over its cross section. Determine the magnitude of the magnetic field in terms of No at a distance r = 12.5cm from the center of the cable. Express your answer using four decimal places. I R1 R2 R3