1. The problem is to express the inequality shown on the number line. 2. The number line shows an open circle at 4, meaning the value 4 is not included. 3. The arrow extends to the left towards negative infinity, indicating values less than 4. 4. Therefore, the inequality represented is $u < 4$. 5. This means $u$ can be any number less than 4 but not equal to 4.