-16+16 is 0 because if you have 16 items in your hand and you take away 16 which is -16 your going to have 0 it would be different if you have -15+16 the answer will be 1 because your taking away 15 from the 16 that you have.
correct me if im wrong but im assuming four just cause if you count what you have all ready not couting the 15 pies. You have at leat 12 and not couting the lemon pies. And from there you basically have to just thing and do the math and I got at least 3 to 5 pies that should be blueberry. srry for my spekling it ducks