conversations.from: human
conversations.value: Can you walk me through the solution of: Marcus had 18 pebbles. He skipped half of them across the lake, but Freddy gave him another 30 pebbles. How many pebbles does Marcus have now?
conversations.from: assistant
conversations.value: Marcus had 18/2 = 9 pebbles left.
  After Freddy gave him more, he has 9 + 30 = 39 pebbles.