1) Compute the modular ratio n. For this problem, the stiffer material (steel) will be transformed into an equivalent amount of the less stiff material (aluminum).

2) Multiply the the width of the actual steel bar (2) by the modular ratio n.

3) Compute section properties based on the transformed cross section.

4) Use the centroid location, the moment of inertia I_z about the z centroidal axis, and the flexure formula to determine normal stresses produced by the bending moment M.