A book store owner randomly samples 100 customers on two separate days to see what their favorite type of book is. The data shows the results of the two samples. Mystery Sports History Total Day 1 38 27 35 100 Day 2 42 24 34 100 The book store owner expects 850 customers. Based on the samples, about how many mystery books will the book store sell? Enter your answer rounded to the nearest whole number in the box.