The answer to the math riddle How did they like the story about towel manufacturing? is "it was very absorbing". Check out how the answer was determined by stating converse, contrapositive and inverse of a statement here.
If the statement is true, then the contrapositive is also logically true. If the converse is true, then the inverse is also logically true. Check out examples here.
Learn the basic geometry. Find out how indirect and algebraic proofs work at Andrews.edu.