text: Question:Betty is saving money for a new wallet which costs $100. Betty has only half of the money she needs. Her parents decided to give her $15 for that purpose, and her grandparents twice as much as her parents. How much more money does Betty need to buy the wallet?
  Response: Betty has only half of the money she needs, which means 100 / 2 = $<<100/2=50>>50.\nHer grandparents gave twice as much as her parents, which means 15 * 2 = $<<152=30>>30.\nSo Betty\'s grandparents gave her 30 + 15 = $<<30+15=45>>45.\nThat means Betty still needs 100 - 45 = $<<100-45=55>>55
  Feedback: The response is incorrect because it has miscalculated the amount of money Betty still needs to buy the wallet. Betty has $50 and her parents gave her $15, so she has $50 + $15 = $65. Her grandparents gave twice as much as her parents, which means they gave her $15 * 2 = $30. Therefore, Betty has a total of $65 + $30 = $95. To buy the wallet, she still needs $100 - $95 = $5, not $55 as stated in the original response.
  
  Given feedback, revise the response