answer: #Person2# ultimately pays by Visa and signs on the line.
documents: #Person1#: The total cost is 850 dollars. How would you like to pay? 
  #Person2#: By credit card. 
  #Person1#: We take Visa and Master Card. 
  #Person2#: Do you take American Express? 
  #Person1#: No, we don't. 
  #Person2#: Ok, I'll use my Visa. Here you are. 
  #Person1#: Thank you. . . please sign on the line.