initial condition:
g+d=700
g=700-d
final condition
d+20=(2g/3)(1/6)
d+20=g/9
9d+180=g, and since g=700-d we can say
9d+180=700-d
10d+180=700
10d=520
d=52, and since g=700-d
g=648
The original number of ducks was 52 and the original amount of geese was 648.
So there were originally (648-52) 596 more geese than ducks.
