Maximum height shall be determined by the following formula: Height of twenty-five feet at all setback lines shall be permitted. For each additional foot of height, an additional three feet of setback in all yards shall be required. Buildings shall not exceed ninety-five feet in height and shall not exceed thirty feet in height within six hundred sixty feet of any area shown as residential in the master plan of the city. (Prior code § 5-2-4(L)(3))