Translate the following inference to logic notation: If it rains, then Sarah is taking a plane. If Robert reads a book, then it is raining. Patricia is writing a letter or Robert is reading a book. It is overcast if and only if Sarah is taking a plane. If Patricia writes a letter, then Sarah is taking a plane. Therefore it is overcast.
p -> q. r -> p. s or r. t <-> q. s -> q. Therefore t.