Hello!
To solve for this expression, first factor the numerator and denominator of each fraction (if applicable). When you separate the factors in the fraction 5x-5/x^2-1, you should result in 5(x-1)/(x-1)(x+1). Then, since the numerator and denominator both have a factor of x-1, those would cancel leaving you with the simplified fraction 5/(x+1). Since the second fraction is already factored, you can now begin cross canceling factors (this is only something you can do in dividing and multiplying fraction). Because your expression is now
5/(x+1)*(x+3)(x+1)/x-1, you can cross cancel any factors from the fractions (cross canceling is canceling out factors that are diagonal from each other in two fractions). When you do, you should cancel out (x+1) in the denominator of 5/(x+1) and the numerator of (x+3)(x+1)/x-1 leaving you with
5/1*(x+3)/(x-1)
Now that you are left with this, you can now multiply straight across leaving you with the answer 5(x+3)/(x-1) or the third answer choice :)
