According to the given information, Let John's present age be "X". 8 years ago John's age was "X - 8". After one year John's age will be "X + 1". Here, after one year, he will be twice the age of his age 8 years ago. So, X + 1 = 2(X - 8) X + 1 = 2X - 16 Taking X right side, 2X - X = 1 + 16 X = 17 Hence, John's present age is "17 years".