D sun umbrella AD=750 DE=210 D 750 ft Letting AC=720-X CE=X 720 210 ft C720 X E AE =720 boardwalk > The triangle AED is right triangle with hypotenuse AD = 750 , one of the leg ED=210 but to complete we need to find AE the other leg of the right triangle using Pythagorean AE + 2102 = 7502 AE- = 7502 - 210- = (750 + 210) (750 - 210) = 960.540 AE = \\ 960 . 540 =720, if AC=720 - x, then CE= x this will simplify the equations so the distance he walks on the sand from point C to D is the hypotenuse of the right triangle ACED whose two legs are x and 210 CD' =x2 + 2102 thus CD =\\ x + 210- then time walking on the sand at 2 ft per second x + 210 2 plus time walking on the boardwalk at 4 ft 720 x must be 4 minutes 45 seconds or 285 seconds. sec 4