###Human: Karina was born in 1970 and she is currently twice as old as her brother. If her current age is 40, in what year was her brother born?, ### Assistant: If Karina is currently 40, and she is twice as old as her brother, then her brother is currently 40/2 = 20 years old.
If Karina was born in 1970, then her brother was born in 1970+20 = 1990 
 So the answer is :  1990