What you really mean is “only if”, not “if and only if”. “B if and only if A” means that B ↔ A, while “B only if A” means that B → A (but not A → B).
(However, the real world implications assumed above are not correct – it is possible to be in a car crash as a passenger in a car, or as a pedestrian or bicyclist hit by a car. So neither A → B nor B → A is true in real life.)
I took a symbolic logic class at Pierce College last spring, but the professor was very fair in her grading. She awarded almost full credit for most assignments as long as you actually tried. I certainly don’t think it’s tough enough that you would fail as most concepts definitely make sense, but as others have said, the proofs that pop up in later on in the course can be quite difficult. I’ve taken several programming courses and some of the logic behind the class made immediate sense to me, but for the life of me, I could not grasp the proofs (I don’t think I ever successfully completed one). Anyway, I don’t think it’s anything to worry about, but you may have to ask the professor for help during office hours if you don’t get the proofs because if you don’t understand the early ones, it’s pretty hard to catch up (trust me, I know)
For future reference, the class was extremely easy (though some of my classmates were having a hard time) and surprisingly fun. Yes some of the proofs can be tedious and time consuming but all in all it was a great experience. I suggest people to take it even though your major may not be philosophy/math/computer science/rhetoric/prelaw/etc.