An outside loudspeaker considered a small source emits

Question

Compute the each part of following problem given below:

Problem: An outside loudspeaker (considered a small source) emits sound waves with a power output of 90 W.

Part I: Find the intensity 10.0 m from the source.

W/m²

Part II: Find the intensity level in decibels at that distance.

dB

Part III: At what distance would you experience the sound at the threshold of pain, 120 dB?

m

I need expert help to solve the above question.