What does that : between the two terms mean? At a guess I would think a "proportion" which is the same as a division.
In any case, the first thing you need to do is add the fraction
As Plato said, the least common denominator is y(y- 1)(y+ 1). Multiply numerator and denominator of the first fraction by y, of the second fraction by y(y+ 1), and of the third fraction by y- 1.