Which phrase describes an unknown or changeable quantity?
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A. 2 o'clock in the afternoon
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B. The height of the building times
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C. 4 quarts in a gallon
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D. 3 feet 7 inches

Astudent draws two parabolas on graph paper. both parabolas cross the x-axis at (–4, 0) and (6, 0). the y-intercept of the first parabola is (0, –12). the y-intercept of the second parabola is (0, –24). what is the positive difference between the a values for the two functions that describe the parabolas? write your answer as a decimal rounded to the nearest tenth