Prove that each argument is valid by replacing each proposition with a variable to obtain the form of the argument. then use the rules of inference to prove that the form is valid. (a) if i drive on the freeway, i will see the fire. i will drive on the freeway or take surface streets (or both). i am not going to take surface streets. : i will see the fire. (b) if i work out hard, then i am sore. if i am sore, i take an aspirin. i did not take an aspirin. : : i did not work out hard.