ChatGPT-3.5 and 4 both got it right. Here’s Mixtral 8x7b’s answer:

> The 18 lbs of bricks weigh more. The weight of an object is determined by its mass and the force of gravity acting upon it, regardless of the material it is made of. In this case, 18 lbs (pounds) is greater than 17 lbs, so the bricks weigh more than the feathers.

Interesting, I just ran other numbers too and got: "26 lb of bricks weighs more than 25 lb of feathers. The weight is directly compared, and 26 lb is greater than 25 lb."