Could you please re explain/clarify the answer to this problem? I don't get the back of the books explanation.
weisbart: Jan. 20, 2015, 5:21 p.m.
Think of it this way, the flea must jump exactly 12 jumps to the right and 8 jumps to the left if he is to land on 4. Why is this? How many ways can he do this? \[\] For the second part, he has an even number of jumps, so is it possible for him to jump to an odd place?