Premise: "A boy in a helmet is riding his tricycle down a grassy gravel path beside a fence."\nHypothesis: "A boy is riding a tricycle down a path."\nDo we know that the hypothesis entailed by the premise?
Let’s work this out in a step by step way to be sure we have the right answer.
yes
If a boy is riding his tricycle then he is riding a tricycle.

.

Therefore, the answer is yes