I've seen some from the Eubanks era. While I haven't seen any with additional answer info, my gut says it was just in parentheses after the reveal sentence (not unlike some MGHSH Squares cards I saw once).
Imagine the following (line breaks and all) in the Manifold 72 font seen on
this page:
WE SURVEYED ONE HUNDRED
WOMEN,
AND WE ASKED THEM...
"HAVE YOU EVER PRETENDED YOUR DOORBELL WAS
RINGING JUST TO GET A LONG-WINDED CALLER
OFF THE TELEPHONE?"
HOW MANY WOMEN ADMITTED THEY HAVE PRETENDED
THEIR DOORBELL WAS RINGING?
THE ACTUAL NUMBER OF WOMEN WHO HAVE
PRETENDED THEIR DOORBELL WAS RINGING
IS _____.
-Jason