The following is available in just about any aerodynamics or performance textbook - you should be able to check one out in your local library if it be of any size.
OAT = SAT
TAT = SAT(1 + kM^2/5)
Often, RAT is used to represent TAT in the equation above with a recovery loss, while TAT defines the full rise with no loss (k = 1).
If you play with your Jeppesen prayer wheel and compare the calculated answers, you should find a pretty close correlation. Temperatures in absolute units.
[ 09 August 2001: Message edited by: john_tullamarine ]