conversations.from: human
conversations.value: Can you guide me through solving this problem: After Betty gave Stuart 40% of her marble collection, the number of marbles in Stuart's collection increased to 80. If Betty had 60 marbles, how many marbles did Stuart have initially?
conversations.from: assistant
conversations.value: If Betty had 60 marbles, she gave Stuart 40/100*60=24 marbles.
  Since the number of marbles in Stuart's collection increased to 80 after Betty gave him 24 marbles, the number of marbles he initially had is 80-24=56