conversations.from: human
conversations.value: A portable battery charger can fully charge a smartphone in 26 minutes or a tablet in 53 minutes. Ana charged her tablet fully and her phone halfway. How many minutes did it take?
  Solve it.
conversations.from: assistant
conversations.value: Ana charged her phone halfway, so she took 26 / 2 = 13 minutes to charge her phone.
  Thus, it took Ana 13 + 53 = 66 minutes to charge her phone and tablet.