Rules of Inference

I don't understand how to apply the first four rules of inference to this statement: "Every piece of reasoning must start somewhere. And if every piece of reasoning starts somewhere, then every piece of reasoning begins with an unsupported premise. Now, if every piece of reasoning begins with an unsupported premise, then all human thinking is based on mere assumption. And if all human thinking is based on mere assumption, then no one can know anything. Therefore, no one can know anything." I started setting it up using the 's' in start, 'b' in begins, 'a' in assumption and 'k' in know.

How many books does Jo own?

Jo announces: "I have more than 999 books." Jean says: "No, Jo! You have fewer than 1,000 books." Mary says: "Jo has at least 1 book." Only one of these statements is true. How many books does Jo own?

How can they get across

Nine men and two boys, trekking through the jungle, need to cross a river. They have a small inflatable boat and it's easy enough to row it across the river. The boat, however, can hold no more than one man and two boys. How can they get all across? (Hint. Suppose there was only one man and two boys).

How do they get across the river

Nine men and two boys, trekking through the jungle, need to cross the river. They have a small inflatable boat and it's easy enough to row it across the river. The boat, however, can only hold no more than one man and two boys. How can they all get across? (Hint: suppost there was only one man and two boys.)

How can they all get across to the river

Nine men and two boys are trekking through the jungle. They need to cross a river but only have an inflatable boat. It is easy enough to row it across the river but can hold no more than one man or two boys. How can they all get across? The hint given is suppose ther was only only man and two boys.