- represent one seed;
+ represent two seeds; and let
( and ) both represent a mouth that will eat one seed if there is anything on offer.
On the left-hand side we get:
1 seed, eaten. Another seed, eaten. Two seeds, one eaten, one left. Another added but then that one is eaten. Remainder = one seed
On the right-hand side the action is much quicker:
A wasted bite (cheating here?!). Two seeds, one eaten. Remainder = one seed