conversations.from: human
conversations.value: Provide a step by step solution for the following math problem: A plumber bought 10 meters of copper and 5 more meters of plastic pipe. If each meter cost $4, how much did the plumber spent on the copper and plastic pipe?
conversations.from: assistant
conversations.value: He bought 10 + 5 = 15 meters of plastic pipe.
  The total meters of the copper and plastic pipe is 10 + 15 = 25.
  The plumber spent $4 x 25 = $100 on copper and plastic pipe.