help...how do you solve this rotational motion problem?

Question

A woman with mass 50.0 kg is standing on the rim of a large disk that is rotating at 0.500 rad/s about an axis perpendicular to it through its center. The disk has a mass of 110 kg and a radius of 4.00 m.

Calculate the magnitude of the total angular momentum of the woman-plus-disk system, assuming that you can treat the woman as a point.

Answer 1

moment of ineteria of a disk is 1/2 mr^2 and of woman Mr^2
so total angular momentum is (1/2m+M)r^2 w