Gerry is reading a book that has 475 pages. He already read some of it last week. He plans to read 160 pages tomorrow. By then, he will be 4/5 of the way through the book. How many pages did Gerry read last week? Which equation bests represents the situation?
w + 160 = (4/5) 475
w + 20 = (2/3) 276
475 = 160 - (4/5) b