conversations.from: human
conversations.value: A merchant bought 15 keyboards and 25 printers for a total of $2050. If a keyboard costs $20, how much does a printer cost?
conversations.from: assistant
conversations.value: 15 keyboards at $20 per keyboard cost a total of 15*$20=$300
  The total cost of printers and keyboards is $2050 so 25 printers cost $2050-$300=$1750
  1 printer cost $1750/25=$70