-How you find the answer is by finding how many times you can arrange the numbers. You cannot have the same arrangement/number in an arrangement twice.
(These are all the arrangements.) -20, 41, 6, -20, 6, 41, -41, 6, 20, -41, 20, 6, -6, 41, 20, -6, 20, 41,
The ratio of the height (h) of the streetlight to its distance to the end of Laura's shadow is the same as the ratio of Laura's height to her distance from the end of her shadow. .. h/(12+9) = 5'4"/9 .. h = (21/9)*5'4" = 12 4/9 feet .. h = 12 ft 5 1/3 inches
