1. The problem asks for the opposite of 145. 2. The opposite of a number $x$ is defined as $-x$. 3. Since the number is 145, its opposite is $-145$. 4. The absolute value expressions $|145|$ and $|-145|$ both equal 145, which is not the opposite. 5. The number 145 itself is not the opposite, it is the original number. **Final answer:** $-145$