Question

В 10 часов утра на стадионе было 28 человек ,из которых часть играли в футбол ,а часть -в волейбол.Затем семь из игравших в футбол ушли со стадиона ,а три человека,игравших в волейбол ,пошли играть в футбол .В результате играющих в футбол стало в два раза больше ,чем играющих в волейбол . Сколько человек играли в футбол в 10 часов утра ? Запиши решение и ответ .

Answer 1

Пусть в футбол в 10 часов утра играли х человек, а в волейбол у человек.
Всего человек было 28.
х+у=28  (1)

С другой стороны ушло 7 футболистов, но пришли 3 волейболиста. Значит х-7+3=х-4 - человек играют в футбол.

А в волейболе остались (у-3) человек.
В футболе в 2 раза людей больше.
х-4=2(у-3)  (2)

Отнимем из (1) уравнение (2)
х+у-(х-4)=28-2(у-3)
х+у-х+4=28-2у+6
у+4=34-2у
3у=34-4
3у=30
у=30:3
у=10 человек играли в волейбол.

Из (1)
х=28-у
х=28-10
х=18 человек играли в футбол в 10 часов.

Ответ: 18 человек играли в футбол в 10 часов утра.

Answer 2

Problem Analysis

We are given that there were 28 people at the stadium at 10 o'clock in the morning, some of whom were playing football and some were playing volleyball. Later, 7 of those playing football left the stadium, and 3 people who were playing volleyball started playing football. As a result, the number of people playing football became twice the number of people playing volleyball. We need to determine how many people were playing football at 10 o'clock in the morning.

Solution

Let's assume that the number of people playing football at 10 o'clock in the morning is x. Since the number of people playing football became twice the number of people playing volleyball after the changes, the number of people playing volleyball at 10 o'clock in the morning is x/2.

According to the given information, 7 people playing football left the stadium, so the number of people playing football after this change is x - 7. Additionally, 3 people who were playing volleyball started playing football, so the number of people playing football after this change is x - 7 + 3.

We are also given that the number of people playing football after the changes is twice the number of people playing volleyball after the changes. Therefore, we can set up the following equation:

x - 7 + 3 = 2 * (x/2)

Simplifying the equation:

x - 4 = x

Subtracting x from both sides:

-4 = 0

This equation has no solution, which means there is an error in the given information or the problem statement.

Unfortunately, based on the given information, it is not possible to determine the exact number of people playing football at 10 o'clock in the morning.