Coding Decoding (BBA)

65 is the correct answer. As per code, sum of position of letters in REPEAT is 18 + 5 + 16 + 5 + 1 + 20 = 65.

It is the correct answer as N is the last letter and C is the first letter in word CHILDREN as the word is written in reverse order.
As per the code, it is written in reverse order like CHILDREN - NERDLIHC.
Therefore, STUDENTS - STNEDUTS.

It is the correct answer as per corresponding letter of each letter (A is opposite to Z and C is opposite to X). 
In CODE, corresponding letters are used as A - Z, C - X, E - V and so on.
CAPITAL - XZKRGZO

4 is the correct answer.

I will pray - 648
He will caring - 452

It is the correct answer. 
As per code, corresponding letters are used in coding as A - Z, B - Y, C - Z and so on.
READYMADE - IVZWBNZWV

It is the correct answer as each letter of the word is one step ahead of the corresponding letter of the code. 
As per code, CDFQDD - DEGREE.

EIINMG is the correct answer.
As per code, the second, fourth and sixth letter will be written first (ARCR) and first, third, fifth and seventh letter will be written in reverse order (seventh, fifth, third and first letter, respectively. NOIPC is the code for CAPRICORN).
Therefore, GEMINI - EIINMG.

42 is the correct answer.
As per code,
W - 23
A - 1
R - 18
WAR means 23 + 1 + 18 = 42.

FMRLM is the correct answer.
As per code, corresponding letters are used as U - F, N - M, I - R and O - L.
UNION - FMRLM

It is the correct answer.
As per code, the second, fourth and sixth letter will be written first.
LETTER - ETRETL

LAWYER is the correct answer.
As per code, the previous letters are used (C - B, O - N) and so on.
KZVXDQ - LAWYER