docs.google.com/document/d/1z7NpDHYFABc6rvHOcE_io3zx0JKYhXhDqGyPpzPEzwI/edit
I changed the doc to "anyone can view" if this doesn't work I can try one more thing I think
hmmm. You should have been ablte to figure this out, given what I said before. You just have to find where the parabolas intersect, and the get the difference between the y-coordinates. Of course, it would have been easier without the typo you had in the first posting ...
-x^2-4x = -3x^2-15x
2x^2+11x = 0
x = 0 or -11/2
y = 0 or -33/4
so the difference is 33/4