Translate the following inference to logic notation: Sarah is not happy. Patricia is poor or Barbara is playing squash. If Patricia were poor, then Jennifer is a janitor. If Karen writes a letter, then Sarah is happy. If Barbara plays squash, then Jennifer is a janitor. Therefore Karen is not writing a letter and Jennifer is a janitor.
~p. q or r. q -> s. t -> p. r -> s. Therefore ~t and s.