###Human: At the bookstore, Sarah bought 6 paperback books and 4 hardback books. Her brother bought one-third as many paperback books as Sarah bought, and two times the number of hardback books that she bought. How many books did her brother buy in total?, ### Assistant: Her brother bought 6/3=2 paperbacks
He bought 4*2=8 hardbacks
In total he bought 2+8=10 books 
 So the answer is :  10