The question is not complete since no map is attached, but I would show you how to solve it.
When trying to determine the location of the epicenter of the earthquake, we need at least three different seismic stations. To find the epicenter, a method known as triangulation is used. This is done by drawing circle at each of the seismic stations with the radius of the circle equal to the distance from the station to the earthquake. The point of intersection of this three circles is the epicenter.
In this problem, a circle with a radius of 380 miles is drawn at Phoenix, 280 miles radius circle at Denver and a 880 miles radius circle at California. The point of intersection of the circle gives the epicenter. Note that the circles are drawn to scale.
