Derivation for symbolic Logic

GMarieB

Help! I have a symbolic Logic class that is really giving me a hard time (numbers are much easier to work with than letters!) I have to give a derivation for the conditional if ~B then ~A, Therefore if A then B. (I don't have a horseshoe symbol on my computer). I am so frustrated, I just want to use Transposition and get it over with but I can't. My professor highly recommends using a Conditional Proof, but I am stumped after I assume B. Any suggestions?? The rules I am allowed to use are the following:
Conjunction
Addition
SImplification
Disjunctive Syllogism
Excluded-Midle Introduction
Commutation
Association
Distribution
Double Negation
De Morgan
Modus Ponens
Modus Tollens
Hypothetical Syllogism
Constructive Dilemma
Transposition
Implication
Exportation
and Equivalence