Question

Abby is half as old as her dad and as twice as old as her brother. if her brother is 9 years old how old is her dad?

Answer 1

Let Abby's father's age be x.
Then Abby's age = 1/2 x or her father's age= 2* Abby's age
Abby's brother's age = 9 years
So, Abby's age= 2*9= 18 years
∴ her father's age = 2*18 =36 years

Answer 2

A=D/2
A=2B
B=9
A=2 (9)
A=18
18=D/2
*2 both sides
D=36