Please answer this question and show all of your work. Thank you!!

V block r = 30.0 cm A circular platform is level and able to spin freely about its center. A spring-loaded launcher is attached to the platform so that it will launch a 15.0 g block at 4.00 m/s from a point that is 30.0 cr from the center of the platform as shown in the diagram here. The platform (including the launcher) has a rotational inertia of 0.0162 kg m. If the platform and block were stationary before the block is launched, what will be the platform's angular velocity immediately after launching the block