Form 1040, Schedule 1, Line Z on my 2023 return shows Qual State Tuition Prgm from 1099-Q $ 645. Turbotax customer support cant tell me how this is calc'd?

I have two 1098Ts (two diff colleges) and two 1099Q's (one issued to my son (payments directly to school) and one issued to me the father (reimbursement for book costs and such).