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
  
  Given that the answer is 5, why is the response wrong?. Write the reason within 200 tokens. Start the response with "The response is incorrect because".