I am having trouble with the following triple integral:

Triple Integral (over E), where E is bounded by the cylinder (y^2) + (z^2) = 9, and the planes x = 0, y = 3x, and z = 0. The density function of the triple integral is defined as f(x, y, z) = z dV.

The biggest problem I am having is defining the boundaries for each integral (i.e. iterating the integral).

Thanks for any help.