Factor every numerator and denominator.
x^2-7x+6= (x-1)(x-6)
x^2-x-30= (x-6)(x+5)
x^2-25= (x+5)(x-5)
x^2-1= (x+1)(x-1)
Simplify the first term by cancelling out (x-6) in both the numerator and denominator
(x-1)/(x+5)* (x+5)(x-5) / (x+1)(x-1)
Now cross simplify cancelling out (x-1) and (x+5)
1/1* (x-5)/(x+1)
Final answer: R