I've been studying Discrete Mathematics from Kenneth Rosen's book. In that book, there is this "$(p \vee q) \land (\neg p \vee r)) \rightarrow (q \vee r)$" proposition if we can say so.
The book wants me to prove that this proposition is a tautology. I've searched on the Internet and also on here but couldn't figure out how to prove this without a truth table. There is another asked question but that is so confusing and is not really illustrative.
Would you help me to prove this, please? Thank you in advance. :)