Retirement tax questions

I am seeing a similar amount.  My payments are $40K more than line 5.  In the worksheet under Qualified Tuition Program (QTP) Computation of Taxable Distribution, line 1 is the amount of distributions from my 1098-Q.  And then there is a line 2c--adjusted qualified higher education expenses--that is about $10K less than my payments.  What is the basis for that adjustment?