The library has two types of books: fiction books and textbooks. Over the last two years, the library has added twice as many fiction books as textbooks. Part 1: Let t be the number of textbooks added to the library over the last two years. Use t to write an expression that describes how many fiction books were added to the library Part 2: Use the expression you wrote in part 1 to write an equation representing the total number of books, n, added to the library. Instead of using a separate variable to represent the number of fiction books, substitute the expression you wrote in part 1 so that the equation is in terms of t. Part 3: If the total number of books in the library added was 3,120, how many of them were textbooks? Write an equation to get the answer.

I would write this (calling the number of fiction books f): Part 1: f=2 tPart 2: n=2 t + tPart 3:3120=2 t + t so 3 t=3120 and t=1040