# Calculation puzzle 011

Find the missing number.

   17   |   8   |   5   |   5
--------------------------------
20   |   4   |   6   |   4
--------------------------------
18   |   3   |   7   |   3
--------------------------------
7   |   ?   |   8   |   2


Source: This question is taken from YTU YOS 2018 exam. I have mentioned those exams in my other posts.