Jose brought eight hats. a week later half of all his hats were destroyed in a fire. there are now only 15 hats left. with how many did he start with

Astudent draws two parabolas both parabolas cross the x axis at (-4,0) and (6,0) the y intercept of the first parabolas 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