Posted by Need Help on .
You need to use parentheses to clarify the meaning of what you wrote. You can't have a four-story fraction with three / signs
x^2+2x-15 factors into (x+5)(x-3)
There is also an (x+5) factor in x^2-25,and an (x-5) factor in 2x-10.
That should lead to some cancellations