[X] 100 Green Stones per year
Yeah, this is not an "investment" investment - it would not bring financial returns, and even any sort if returns in "more scholars" would not be that big probably.
This is buying the influence - throwing your name out there, probably getting aquianted with other donors, getting Ling clan associated with investing in schools (in capital). More or less demonstrating good taste and refinement to other nobles, and also showing that Ling family can afford to throw their money on something like this (on something that would not give short-term benefits).