Alfonso earns $6 each day walking his aunt’s dog. He is saving to buy a mountain bike helmet for $340. Currently, he already has $40. If he walks his aunt's dog 5 days a week, in how many weeks should Alfonso work to buy his mountain bike? Let's think first. Chain of thought:
Alfonso has to work for the $340 - $40 = $300. In a week, he earns $6 x 5 = $30. Thus, he needs to work $300 / $30 = 10 weeks to buy the bike.
Therefore, the answer is 10.