Two coherent sound waves have intensities of 0.040 W/m2 and 0.090 W/m2 where you are listening. (a)

Question:

Two coherent sound waves have intensities of 0.040 W/m2 and 0.090 W/m2 where you are listening.
(a) If the waves interfere constructively, what is the intensity that you hear?
(b) What if they interfere destructively?
(c) If they were incoherent, what would be the intensity? [If your answers are correct, then (c) is the average of (a) and (b).]