+526 
Let's consider this graph
So as you can see the seismographs are placed at \(A(-2,5), B(2,3)\) and \(C(-2,-4)\).
From the question,
Epicentre is located 2 miles from A, 4 miles from B & 7 miles from C
∴ Eliminating all possibilities, epicentre is located at \(E(-2,3)\).
~Amy
