I would like help with these problems please

Suppose that two people standing 4 miles apart both see the burst from a fireworks display. After a period of time, the first person standing at point A hears the burst. Three seconds later, the second person standing at point B hears the burst. If the person at point B is due west of the person at point A and if the display is known to occur due north of the person at point A, where did the fireworks display occur? Note that sound travels at 1100 feet per second. The fireworks display is feet north of the person at point A. (Do not round until the final answer. Then round to the nearest foot as needed.)