If the ratio of a to b is r, then express the ratio of a + b to a - b in terms of r.
Hmmm..
Yay now I figured it out!!!!
We know that a/b = r
Then a = rb
so a + b = rb + b = b(r + 1)
a - b = rb - b = b(r - 1)
Therefore the ratio is (b(r+1))/(b(r-1))
This is just (r+1)/(r-1)
And that's the answer!!!!!