Question

у петра дисков в 4 раза меньше, чем у Кирилла. если Кирилл подарить сестре 15 дисках, то у мальчиков дисков станет поровну. Сколько дисков у Петра ?

Answer 1

Х-дисков у Петра
Х=4Х-15
15=4Х-Х
15=3Х
Х=5
Ответ: 5 дисков у Петра

Answer 2

Problem Analysis

We are given that Peter has four times fewer disks than Kirill. If Kirill gives his sister 15 disks, then the number of disks will be equal between the boys. We need to determine how many disks Peter has.

Solution

Let's assume that Kirill has x disks. According to the given information, Peter has four times fewer disks than Kirill, so Peter has x/4 disks.

If Kirill gives his sister 15 disks, then the number of disks will be equal between the boys. This means that after Kirill gives away 15 disks, both Kirill and Peter will have the same number of disks.

We can set up the following equation to represent this situation:

x - 15 = x/4

To solve this equation, we can multiply both sides by 4 to eliminate the fraction:

4(x - 15) = x

Expanding the equation:

4x - 60 = x

Now, we can subtract x from both sides:

4x - x = 60

Simplifying:

3x = 60

Dividing both sides by 3:

x = 20

Therefore, Kirill initially has 20 disks. Since Peter has four times fewer disks than Kirill, Peter has 20/4 = 5 disks.

Answer

Peter has 5 disks.

Explanation

According to the given information, Peter has four times fewer disks than Kirill. If Kirill gives his sister 15 disks, then the number of disks will be equal between the boys. By solving the equation, we find that Kirill initially has 20 disks and Peter has 5 disks.