The logic behind this puzzle is to add up all the individual digits of the numbers on the left side of the equation to get the result on the right side.
14 + 62 = 13 ⇒ (1 + 4) + (6 + 2) = 5 + 8 = 13
25 + 73 = 17 ⇒ (2 + 5) + (7 + 3) = 7 + 10 = 17
36 + 84 = 21 ⇒ (3 + 6) + (8 + 4) = 9 + 12 = 21
Applying this exact same pattern to the final equation:
