Sophia finished 2/3 of a book. She calculated that she finished 30 more pages than she has yet to read. How long is her book?  Choose the correct choice:  A) 90  B) 150  C) 130  D) 190  E) 210

Rationale: "let x be the total number of pages in the book , then she finished 2 / 3 * x pages . then she has x − 2 / 3 * x = 1 / 3 * x pages left . 2 / 3 * x − 1 / 3 * x = 30 1 / 3 * x = 30 x = 90 so the book is 90 pages long . answer is a ."
Answer: A