All you have to do is set up an equal proportion [tex]\frac{height}{length}[/tex] or [tex]\frac{x}{180 inches(15 feet)}[/tex] = [tex]\frac{85}{51}[/tex] cross multiply to get 51x = 180*85 which is simplified to 51x = 15300 divide both sides by 51 to get x = 300 inches. Since the answer choices are in feet, divide 300/12 to get 25 feet
