To find out how many how-to books are in the school library, you need to multiply the total number of books in the library by the proportion of how-to books. Here is how you can calculate it:
1. Determine the total number of books in the school library: let's say it is 'x'.
2. Calculate the number of how-to books: multiply 'x' by the proportion of how-to books, which is 0.3 (since how-to books make up 0.3 of the books in the library):
Number of how-to books = 0.3 * x
3. Find out how many of these how-to books deal with carpentry: multiply the number of how-to books by the proportion of carpentry books, which is 0.2 (since 0.2 of the how-to books deal with carpentry):
Number of carpentry books = 0.2 * (0.3 * x) = 0.06x
4. Calculate how many how-to books deal with electronics: multiply the number of how-to books by the proportion of electronic books, which is 0.4 (since 0.4 of the how-to books deal with electronics):
Number of electronics books = 0.4 * (0.3 * x) = 0.12x
Therefore, in the school library, there are approximately 0.06x books on carpentry and 0.12x books on electronics, where 'x' represents the total number of books in the library.
How-to books make up 0.3 of the books in the school library. Of these, 0.2 deal with carpentry and 0.4 deal with electronics.
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