subtract: 4x/x^2-25 - 2/x^2+2x-15
a. 4x^2-14x+10/(x+5)(x-3)
b. 4x^2-14x-10/(x-5)(x+5)(x-3)
c. 4x^2-14x-10/(x-5)^2(x-3)
d. 4x^2-14x-10/(x-5)(x+5)(x-3)