At first, Mr Menon had 380 more books than magazines in his bookshop. He then sold 1/4 of the books and 3/5 of the magazines. The number of books left was 600 more than the number of magazines left. What was the total number of books and magazines Mr Menon had at first?
B = M + 380
0.75 B = 0.40 M + 600
so
0.75 (M+380) = 0.40 M + 600
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