[nbclark]

Couldn't the book cost 7.5k and one has 6.5 and the other has 0.5? Along those lines, isn't anything in the range of costing 7->8 (non-inclusive) acceptable (e.g. 0.9k and 6.9k)?

[bentcorner]

I was wondering the same thing but Kopecks are not currently subdivided.

https://en.wikipedia.org/wiki/Kopek

[Arnavion]

The second question's solution requires half-kopeks.

[scotty79]

These problems aren't current or modernized. There's no way a bottle with a cork in problem #2 costs 10 kopek.

current 10 kopek is worth 0.0013$

They probably come from time when 0.5 kopek was the smallest coin.

#1 problem doesn't have single non-zero solution if the smallest coin has larger or smaller.