conversations.from: human
conversations.value: Provide a step by step solution for the following math problem: John decides to buy new phones for him, his 2 kids, and his wife.  Each phone after the first 2 is half price.  If the phone price is $600 how much did he pay for them all?
conversations.from: assistant
conversations.value: He bought 1+2+1=4 phones
  2 of the phones cost 600 so their cost is 2*600=$1200
  The other two phones cost 600/2=$300
  So they cost 300*2=$600
  So the total cost is 1200+600=$1800