What was the question for this implicit rationale, and corresponding answer?
Michael has used a total of 30 matchstick houses * 10 matchsticks per matchstick house = 300 matchsticks. As he only used half of his collection for crafting, he must have originally had 300 matchsticks * 2 = 600 matchsticks.
 The answer: 600
The question: Michael has a lot of matchsticks at home and decides to use them to make miniature models. As he is about to start crafting, he has second thoughts and decides to only use half of his pile of matchsticks. He creates 30 matchsticks houses. If he has now used all of the matchsticks he intended to and each matchstick house uses 10 matchsticks, how many matchsticks did Michael have originally?