Answer: w < 8
w is a place holder for the cat's weight. It's some positive real number.
To describe all weights less than 8, we simply write w < 8.
For example, let's say the cat weighs 5 pounds. This would mean w = 5. In other words, 5 replaces w and we go from w < 8 to 5 < 8. This is a true inequality because 5 is smaller than 8.
Something like 10 < 8 is false because 10 is not less than 8. So w = 10 is not a solution to w < 8.