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There are 1500 literature and art books in the library, 30 less than 3 times of science and technology books. How many science and technology books are there?
Suppose that there are x science and technology books, & nbsp; & nbsp; 3x-30 = 1500, 3x-30 + 30 = 1500 + 30, & nbsp; & nbsp; 3x △ 3 = 1530 △ 3, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; X = 510, answer: there are 510 science and technology books
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