A girl is c years old. Her brother is twice as old. How old will the brother be in d years time?

The brother's age is 2c. In d years time, his age will be 2c + d.

To determine how old the brother will be in d years, we need to find out his current age and then add d to it.

Given that the girl is c years old, the brother is twice as old. Therefore, the brother's current age is 2c.

To find out how old the brother will be in d years, we add d to his current age:

Brother's age in d years = 2c + d

So, the brother will be 2c + d years old in d years time.