For this chain-of-thought reasoning and answer, what was the question?
He had 40 - 16 = 24 left after using some. Then after giving some away he is left with 24 / 2 = 12.
 A: 12
Q: John buys a box of 40 light bulbs. He uses 16 of them and then gives half of what is left to a friend. How many does he have left?