Premise: "A man riding on the back of a trash truck."
Hypothesis: "The man is a city sanitation employee."
Do we know that the hypothesis entailed by the premise? A step-by-step solution is:
Sentence one states the man is riding in the back of a trash truck. Just because he is a sanitation employee doesn't mean he rides in the back of a trash truck.
The final answer: it is not possible to tell.