Answer: 39
Explanation: considering the fact that the sum of his age next year will be a third of the sum this year, the only way for this to be possible is if the second digit next year is zero (0) which means this year, the second digit is 9.
Going through the variables, only 3 and 9 fulfils all parameters. The sum of 3 and 9 equals 12 which is 3times the sum of age next year, 40 which is 4 and 0.
12÷4 = 3
He is 39 this year.
