Xiao Ming weighs x kilograms, and his father weighs 30.5 kilograms, which is more than twice that of Xiao Ming. How much does his father weigh? When his father weighs 80.5 kilograms, how many kilograms does Xiaoming weigh?
Solution: Dad weighs (2x+30.5) kg.
When dad's weight is 80.5 kg, Xiao Ming's weight is:
2x+30.5=80.5
2x=50
x=25
A: Dad weighs (2x+30.5) kg, and Xiaoming weighs 25 kg.