Question 1201030
...1000 adults...<pre>(yes's) + (no's) + (not sure's) = 1000
   x    +   y    +     z        = 1000</pre>...340 answered "no" or "not sure."...<pre>(no's) + (not sure's) = 340
   y   +      z       = 340</pre>...the number of those who answered "yes"
exceeded the number of those who answered
"no" by 400...<pre>(yes's) - (no's)  = 400
   x    -   y     = 400

Edwin</pre>