At all points where there is an electric field it is radially outward. For each part of the problem use a spherical gaussian surface, centered about the center of the actual spheres, and passing through the point where the field is to be found.
a) Charge enclosed is q (r/a)3 for r < a.
b) Charge enclosed is q for a < r < b.
c) The shell is conducting.
d) Charge enclosed is zero.
e) For b < r < c , the electric field must be zero; a gaussian sphere with this radius must enclose no net charge.