Translate the following inference to logic notation: Thomas is an artist or Sarah is playing a game. If Sarah plays a game, then Barbara is a sailor. If Thomas were an artist, then Barbara is a sailor. Sarah is not working. William is writing a letter if and only if Sarah is working. Therefore Barbara is a sailor and William is not writing a letter.
p or q. q -> r. p -> r. ~s. t <-> s. Therefore r and ~t.