###Human: Two-thirds of the class have brown eyes. Half of the students with brown eyes have black hair. If there are 6 students in the class with brown eyes and black hair, how many students are there in total?, ### Assistant: There are 6 * 2 = 12 students with brown eyes and hair of any color.
There are 12 * 3/2 = 18 students in total. 
 So the answer is :  18