The location of a ship can be found with the use of a hyperbolic model with the path of the ship being described by the hyperbola having two different stations serving as the foci. of the center of the hyperbola is at the origin (i. e., the point (0, 0) on a coordinate plane), and the stations are 204 miles apart, find the equation of the hyperbola if the ship is 90 miles east of the origin.