The line of sight of a level falls at a rate if 0.122ft/ 100 ft when the level bubble is centered. A backsight of 4.782 is taken on point A, which is at 75 ft from the level. the elevation of a is 425.238 ft. A foresight of 5.162 ft is taken on point B, which is 190 ft from the level. If the bubble was centered for both the backsight and the foresight, what is the elevation of B? neglect curvature and refraction