You're given as input four integers in the form `(a,b)` and `(c,d)`.

Determine whether it's possible to get `(c,d)` from `(a,b)` if at each step you can choose between the operation `(a+b,b)` or `(a,a+b)`.

So, for example, `(1,2) -> (3,2) -> (5,2) -> (5,7) -> (12,7) -> (12,19) -> ...`

I tried solving something with a+b*x = c and a*x +b = d, but that didn't work. Any ideas?