Warrant Deed Question Need ASAP answer

I am having a owner convey a property to me by way of a warranty deed. I am paying $15000 in back taxes and giving the owner $500 in cash. On the warranty deed is says: Grantor does hereby swear or affirm that the actual consideration for this transfer or value of the property transferred, whichever is greater, is $ ____________ which amount is equal to or greater than the amount which the property transferred would command at a fair voluntary sale. What do I put in the blank? $500 $15500? Or does it need edited? Please help. Must get in the mail tomorrow. Thanks, Tim