What is the missing number in this number sequence pattern?

[kardo]

TL;DR Summary

pattern numbers

these are a pattern of number sequence asked in assessment for new employee , what could be the missed number
9 1 6 4
4 5 7 2
5 8 8 5
1 3 5 X

is says the equation could be limited to (addition, subtraction, division and multiplying)

 

[anuttarasammyak]

Spoiler

9-6=4-1
4-7=2-5
5-8=5-8
1-5=X-3
X=-1

 

[martinbn]

TL;DR Summary: pattern numbers

these are a pattern of number sequence asked in assessment for new employee , what could be the missed number
9 1 6 4
4 5 7 2
5 8 8 5
1 3 5 X

is says the equation could be limited to (addition, subtraction, division and multiplying)

Is the solution unique?

Here is one

9 + 1 = 6 + 4
4 + 5 = 7 + 2
5 + 8 = 8 + 5
1 + 3 = 5 + X

 

[fresh_42]

Please refrain from posting questions and answers (!) that could affect decisions in real life.

We don't do it in case of car accidents, so we shouldn't do it in the realm of assessments. Furthermore, we do not solve homework questions, of any kind.

Thank you.