Logic: Next number ( Even Placed ) = Previous Number + Sum of the digits of previous number.Next number ( Odd Placed ) = Previous Number + Sum of the digits of previous number - 12.79 = 71 + 7 + 1 ( Even Placed )67 = 79 + 7 + 9 -12 ( Odd Placed )80 = 67 + 6 +7 ( Even Placed )68 = 80 + 8 + 0 - 12( Odd Placed )x = 68 + 6 + 8 = 82( Even Placed )Thus, Missing number = 82.