Algebra Problem:

Question

The number of science books checked out at the school library is directly proportional to the number of students in Physics class. If 42 books were checked out when 6 students were in physics class, how many books were checked out when there were 11 students in the class?

(A) 66 books

(B) 47 books

(C) 53 books

(D) 77 books

(E) None of these

For this I got (D) 77 books, is this correct?

Answer 1

That's what I got :

6/42 = 11/x

6x = 462 (cross multiply)

x = 77

Answer 2

(D) How do you know each kid got the same amount?