Xiaoming's younger brothers are triplets. Xiaoming's age this year is equal to the total age of the 3 brothers. In 6 years, the total age of the 3 brothers will be twice Xiaoming's age. Xiaoming is $\qquad$ years old this year.
I Analysis and Solution I Age Problems, Difference and Multiple Problems.
( Method One )
Xiaoming's age this year is equal to the total age of his 3 younger brothers;
Therefore, in 6 years, the total age of the 3 younger brothers will be $6 \times 3-6=12$ years more than Xiaoming's age;
And in 6 years, the total age of the 3 younger brothers will be 2 times Xiaoming's age;
Thus, in 6 years, Xiaoming's age will be $12 \div (2-1)=12$ years; Xiaoming is $12-6=6$ years old this year.
( Method Two )
Let Xiaoming be $x$ years old this year; According to the problem, we have $2(x+6)=x+6 \times 3$; Solving for $x$ gives $x=6$; Xiaoming is 6 years old this year.