Barbara wants to save up for a new wristwatch that costs $100. Her parents give her an allowance of $5 a week and she can either save it all up for the watch or spend it as she wishes. 10 weeks pass and due to spending some of her money on ice cream, Barbara currently only has $20. How many more weeks does she need to save for a watch if she stops spending on other things right now? Let's think first. Chain of thought:
Since barbara needs $100, and she currently has $20, she is remaining with $100 - $20 = $80 to save. With an allowance of $5 each week, she'll need to save for 80 / 5 = 16 weeks.
Therefore, the answer is 16.