The average age of Dongdong, his father and his mother this year is 30 years old. It is known that the average age of his father and his mother is 39 years old. How old do you guess Dongdong is this year?

The average age of Dongdong, his father and his mother this year is 30 years old. It is known that the average age of his father and his mother is 39 years old. How old do you guess Dongdong is this year?

30 × 3-39 × 2, = 90-78, = 12 years old

Xiaoming and his parents are now 61 years old. A year ago, his father's age was equal to the sum of Xiaoming's and his mother's ages. This year, ask Xiaoming, his father and his mother each
How old? No equation

61 minus 3 times 1 equals 58 58 divided by 2 equals 29 29 plus 1 equals 30. That's dad's age this year
61 minus 30 equals 31
Later, due to the incomplete information and conditions, the age of mother and Xiaoming could not be calculated directly

Xiao Ming's age is 9 years old. The sum of his parents' ages is 8 times that of Xiao Ming. His father is 2 years older than his mother. Xiao Ming's father is () years old, and Xiao Ming's mother is ()
10 years old? 10 right

Xiaoming father: 37 mother: 35