conversations.from: human
conversations.value: Can you give me some step-by-step instructions for this math problem: Tas and his friends put up a t-shirt for sale. They ended up selling 200 t-shirts in 25 minutes. Half of the shirts were black and cost $30, while the other half were white and cost $25. How much money did they make per minute during the sale?
conversations.from: assistant
conversations.value: The total revenue from black shirts was 100 * $30 = $3000.
  The total revenue from white shirts was 100 * $25 = $2500.
  The total revenue from all shirts sold was $3000 + $2500 = $5500.
  Tas and his friends ended up making $5500 / 25 minutes = $220 per minute.