(5 x 9) + 1 = 46

Similarly, (7 x 11) + 1 = 78.

(31 x 2 - 6) = 56

and (45 x 2 - 9) = 81

and 5 x 7 x 4 = 140

Therefore, 4 x 4 x ? = 96

? = (96/16) = 6.

Sum of numbers in upper half of the circle = ? + 4 + 5 + 6 = ? + 15

Upper half = Lower half

30 = ? + 15

? = 30 - 15

? = 15.

Threfore, 15 is the answer.

How the number is obtained?

2 + 4 = 6

5 + 9 = 14

Similarly,

3 + 5 = 8

Therefore, the answer is K₈.

and 789 - 543 = 246

Similarly, 863 - 241 = 622.

10 - 4 = 6

18 - 10 = 8

18 - 4 = 14

For second triangle,

14 - 8 = 6

22 - 14 = 8

22 - 8 = 14

For third triangle,

11 - 5 = 6

15 - 11 = 4

15 - 5 = 10.

From II row, 2 + (2/3) = 8/3

From III row, 3 + ? = 19/5

? = (19/5) - 3

? = (4/5).

79 - (38 + 4) = 37

Therefore, 67 - (16 + X) = 42

X = 9

and (6 + 2 + 10 + 8) - 2 = 24

Therefore, (4 + 14 + 12 + 10) - 2 = 38.