Answer:
13/30
Step-by-step:
First, you find the common denominator, which is 30. For the first fraction, multiply the bottom by five. Since you do that, you have to multiple the top by 5 as well, giving you 25/30. For the second problem, you multiple the top and bottom by six giving you 12/30. 25 minus 12 is 13 so you get 13/30.
Ok... so this question can be solved by using simultaneous equations.
Use the general from of a parabola

you know the value of c, the y-intercept... y = -4
which means the equation is

now use the other 2 points to get 2 equations in 2 unknowns
(-2, -20) just substitute

this becomes

now the other equation using (4, -20)
The simplified form is
10x(3x^2)
15x^2(2x)
5x(6x^2)