Which one will replace the question mark?

(5 x 3) + 4 = 19

and (6 x 4) + 5 = 29

Therefore, (7 x 5) + 6 = 41

(7 x 3) = 21 and (9 x 3) = 27

and (4 x 9) = 36 and (2 x 9) = 18

Therefore (9 x 6) = 54 and (4 x 6) = 24.

(2)² + (4)² = 20

and (3)² + (9)² = 90

Therefore (1)² + (5)² = 26.

(1)² + (5)² + (4)² + (3)² = 51 x 10 = 510

and (3)² + (4)² + (6)² + (2)² = 65 x 10 = 650

Similarly (0)² + (1)² + (2)² + (8)² = 69 x 10 = 690.

(4 + 8) x 9 = 108

(5 + 4) x 12 = 108.

(12 + 18 + 30)/10 = 6

(16 + 24 + 40)/10 = 8

Similarly, (45 + 18 + 27)/10 = 9.

5 x 8 x 10 = 400

and 6 x 9 x 7 = 378

Therefore 5 x 7 x ? = 315

? = 9.

The numbers are squared in ascending order

In first circle,

(3)² = 9

(4)² = 16

(5)² = 25

(6)² = 36.

In second circle,

(4)² = 16

(5)² = 25

(6)² = 36

(7)² = 49.

In third circle,

(6)² = 36

(7)² = 49

(8)² = 64

(9)² = 81.

(16)² = 256

Therefore, (2)² = 4.

(7 x 3) + 8 = 29

(4 x 3) + 7 = 19

(5 x ?) + 6 = 31

? = 5.