Both exams are taken into account with varying percentages. The first exam consisted of Turkish, Maths, Science and Social Studies. For a Foreign Languages student like myself, Turkish makes up for %14, Maths %7, Social Studies %9, Science %5. The second exam was only English for me, it makes up for %65. Your graduation point average is added by a special formula. I did very well on the second one (got 78 out of 80 questions right) but I was very disappointing on the first one because I pretty much didn't study all year.
I was placed 1558th in the country, which is actually pretty damn good (over 200k Foreign Languages students took the exams), but I want to get into the best public school department of my field.