Identify vertex of -3(x-(5/2))^2+(359/4)

Hi my sisters and brothers can tell me the answer because i don’t understand the question

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

Measure a and b and find their sum. how are the angles related?