37 12 21 38 81 14 What is the difference between the resultants of the two rows?

Rules
(i) (2-digit odd number) + (2-digit odd number)
(ii) 2-digit even number → 2-digit perfect square odd number then, (odd number) - (Even number)
(iii) (3-digit number) ÷ (2-digit number)
(iv) (Prime number) + (Even number)
(v) (Even number) x (Even number)
Solution:
1st Row 37   12   21 ⇒ 37 + 12 = 49     [rule (iv)]
⇒         49 + 21 = 70 [rule (i)]
2nd Row 38   81   14 ⇒ 81 - 38 = 43     [rule (ii)]
⇒         43 + 14 = 57 [rule (iv)]
∴ Required difference = 70 - 57 = 13