Mikel asked her father how old he is gues the father said I you add the digits that make my age this year you'll get a number three times bigger than if you do it next year how old is the father

For the sum of the digits of Michelle's father to drop to 1/3 of its' former value, the second digit must go from 9 to 0, in one year.

Thus, if he is 39 this year, the sum of the digits of his age will be 12. Next year, when the sum of the digits would be 4+0, or 4, then the digits of his age would be 1/3rd of their former value.

Therefore, he is 39, and will be 40 next year