conversations.from: human
conversations.value: Martha has 19 butterflies in her collection. She has twice as many blue butterflies as yellow butterflies. The rest of her butterflies are black. If Martha has 6 blue butterflies, how many black butterflies does she have?
  Give me a solution to this problem
conversations.from: assistant
conversations.value: Martha has 6/2=3 yellow butterflies.
  Martha has 6+3=9 blue and yellow butterflies.
  Martha has 19-9=10 black butterflies.