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## Question

primary 6 | Maths
| Algebra

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K: Average cost is $25

Pretend all the books that E bought cost $21 and all the books that K bought cost $25.

K bought 1 more book than E

K paid $57 more than E

If K bought one less book, he would have paid $25 less.

Then, E and K would have bought the same number of books and K would have paid $32 more than E.

Each book by K would be $4 more than each book by E.

By calculation, 8 books by K would be 8 x 4 = $32 more than 8 books by E.

So E bought 8 books.

K actually bought 9 books.

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