Verbal Reasoning - Mental Ability Questions

ROUTINE IS 7 LETTER WORD.. (1st=R,2nd=O,3rd=U,4th=T,5th=I,6th=N,7th=E)
1st and 3rd letter interchanging. (UORTINE)
5th and 7th letter interchanging. (UORTENI)
1st letter shifting one after that (VORTENI)
2nd letter shifting two befor that (VMRTENI)
3rd letter remains same (VMRTENI)
4th letter
(total alphabets - current)+1
(26 - 20)+1= 7.(i.e) G (VMRGFNI)
5th letter shifting one after that (VMRGFNI)
6th letter shifting two befor that (VMRGFLI)
7th letter remains same (VMRGFLI
Like that,
CRUELTY IS 7 LETTER WORD.. (1st=C,2nd=R,3rd=U,4th=E,5th=L,6th=T,7th=Y)
1st and 3rd letter interchanging. (URCELTY)
5th and 7th letter interchanging. (URCEYTL)
1st letter shifting one after that (VRCEYTL)
2nd letter shifting two befor that (VPCEYTL)
3rd letter remains same (VPCEYTL)
4th letter
(total alphabets - current)+1
(26 - 5)+1= 22.(i.e) V (VPCVYTL)
5th letter shifting one after that (VPCVZTL)
6th letter shifting two befor that (VPCVZRL)
7th letter remains same (VPCVZRL).

The answer is 'mare' because a "mare’s nest" doesn't exist just like "hen's teeth" don't exist.