soln from P.C.S. CREATION in comments
(21+6) – (21/3)= 27-7= 20
(36+8)-(36/3)= 44-12=32
(9+12)-(9/3)= 21-3=18
(4+3) – ( 3/3 )= 7 – 1 =6

it follows this pattern
axa = (a-1) + (a-1)

thus 6×6 = 5 + 5 = 10

Answer is 71

as numbers add upto a multiple of 10 in every atom.

ex. 0 + 3 + 14 + 2 +1 =20
2 + 10 + 24 + 6 + 8 = 50
only option which can make the sum to a multiple of 10 for 4 + 14 + 5 + 6 is 71.

answered by Ram Balaji in disqus comments

Its actually pretty simple

all the rows sum is 15

first row => 9 + 1 + 5 => 15
second row => 4 + 8 + 3 => 15
third row => 2 + ? + 7 => 15 => ? = 15 – 7 -2 => 6

from clue 3 and 4 -> 1 number can be 7 OR 3 (since 9 is not correct). Now if 7 was correct and placed in proper spot, it conflicts with Clue 1, thus 7 can’t be the correct number and the correct number is 3 and placed at proper spot (which is 3rd spot).

Now from 2nd clue -> two numbers are correct, one is 3 and other one should be 1 (as we know 7 can’t be correct number), since 1 is placed at wrong spot, correct spot for 1 should be first (since 3rd spot is for 3).

Again from Clue 1: 1 number is correct and placed at wrong spot. we are looking for a number at 2nd spot, it should be 5 (as 7 is not in picture and it can’t be 2 since it is placed at 2nd spot), 5 is placed at wrong spot, its correct spot should be 2nd, since we already know 1st and 3rd spot numbers.

Thus the PIN is 153.

it follows this equation
((second digit -1 )*2 + first digit)*12
ex.
4,3 => ((3-1)x2 + 4)x12 => (4+4)x12 => 96
thus
7,3 => ((3-1)×2 + 7)x12 = 11*12= 132

Answer: 4
Explanation: Diagonal numbers are multiplication of the bottom number and 3
8*3 = 24
5*3 = 15
x*3 = 12 =? x = 4