one answer can be 3 because 5+1=6.. 4+1=5 ?+1=4 so ?=3

can be 6 ...another possibility is 6 because 8-5=3 and 7-4=3 and 9-?=3 gives ?=6

can be 14 also ..yet another analogy is sum of all the number in first set is 26, in the second set 27 and if in the third set 28, ?=14 which has remote chance because all others are single digit. may be another answer depends upon what analogy the question setter has relied on.