By the end of 2015 37 books were in a cupboard at Lena, it read some of them and did not read some. In January it read four books, and presented it on the first of February 3 books which she did not read and Lena noticed that now the read books at it are 3 times more than those which she did not read how many Lena had read books in a case at the end of 2015?

7
1) 37-4=33 (kN) - read and did not read for 2015 2) 33+3 =36 (kN) - after 3) 36:4=9 (kN) - not read 4) 9*3=27 (kN) the answer. at Lena in a case was the read 27 books we do check: 27+9=36 (kN) at us turned out that when presented it 3 books read it was 3 times more
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