This year, Xu Peng is 30 years younger than his father. Four years later, his father was three times as old as Xu Peng. How old are Xu Peng and his father this year?
Answer: Suppose Xu Peng is X years old and his father is x+30 years old.
x+30+4=(x+4)×3
x+34=3x+ 12
3x-x=34- 12
2x=22
x = 22 \2
x= 1 1
Dad's age = x+30 =11+30 = 41year.
A: Xu Peng is 1 1 year old this year, and his father is 4 1 year old.