The daughter is 10 years old, and the parent is 40 years old.
Solution:
Let the daughter’s age be x, and the parent’s age be 4x.
In 20 years:
- The daughter’s age will be x + 20.
- The parent’s age will be 4x + 20.
The parent will be twice as old as the daughter:
4x + 20 = 2(x + 20)
Simplify:
4x + 20 = 2x + 40
4x – 2x = 40 – 20
2x = 20
x = 10
So, the daughter is 10 years old, and the parent is 4 × 10 = 40 years old.
