In 8 years you will be twice as old as your brother.
Right now, your brother is 4 years old, and 4 x 4 is 16, so you are 16.
In two years, your brother would be 6, and you would be 18, making you 3 times as old.
So, in 8 years, your brother will be 12 years old, making you 24. 12 is half of 24.
