Problem 5. Ana wants to buy several pencils. If she buys 6 pencils, she will have 7 denars left, but if she buys 10 pencils, she will be short of 5 denars. How much does each pencil cost, and how many denars did Ana have?
Solution. Let one pencil cost $x$ denars. Then, from the condition of the problem, we have $6x + 7 = 10x - 5$, which simplifies to $4x = 12$ or one pencil costs $x = 3$ denars. Ana had $6 * 3 + 7 = 25$ denars.

## V grade - nine-year-old