Rule department scholar

[It is known that Lin Xiaoqing can lift a weight of [-] catties, what is the arm strength of classmate Lin Xiaoqing? 】
Answer: The left arm is 49 catties, and the right arm is 67 catties.
[It is known that one plus one equals two, what is the result of multiplying 491 by 709? 】
Answer: 348119.
Other people's logic is derivation; mine is causation.When difficult questions are asked, the answers are obvious.