Mrs. Park has 3 boxes of crayons. Each box has 12 crayons. Mrs. Park takes c crayons out of each box. Which expression can be used to find the total number of crayons left in these boxes?

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