Which graph displays a rate of change of 2.5? On a coordinate plane, a line with negative slope goes through points (negative 2, 0) and (negative 1, negative 2).
On a coordinate plane, a line with negative slope goes through points (0, negative 3) and (2, 2).
On a coordinate plane, a line with positive slope goes through points (0, 1) and (2, 2).

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