Cathay Infant fare is 25% of full fare class ticket, and you can't just quote it, you need first to have an adult fare.

It used to be 10% of full-fare class of travel, but they've changed to 25% years ago.

I think FT has an argument about this, with some people thinking it's a great policy to limit infants and others think it's a tragedy of raising the fare to 25%.