what does this mean A=fc/Qb/Qt-1=68.7672

This one makes no sense to me  and since no one else has answered it i am assuming  it makes no sense to anyone else either!

This is an equation relating to the Gateway Arch in St.Louis.......I don't know if the poster wanted an answer or was just curious as to what it was (I wouldn't know how to give one, anyway).....but I guess if he/she were interested, they could look at this page:

http://scotttreleaven.tripod.com/stlouisarchpage/id4.html

thank you Chris.