Question

Б) Сейчас брату 5, лет а через 3 года ему будет в 2 раза меньше лет, чем сестре. Сколько лет сестре сейчас? в) Сейчас брату 5 лет, а год назад ему было в 3 раза меньше лет, чем сестре сейчас. Сколько лет сестре сейчас? г) Сейчас брату 5 лет, а год назад ему было в 3 раза меньше лет, чем сестре сейчас. Сколько лет сестре сейчас?

Answer 1

б) сейчас брату  --- 5 лет

будет через 3 года ---- в 2 раза < , чем будет сестре

сестре  сейчас ----- ? лет

Решение:

5 + 3 = 8 (лет) ----- будет брату через три года

8 * 2 = 16 (лет) ---- будет сестре через три года

16 - 3 = 13 (лет) ---- сестре сейчас

Ответ: 13 лет

Проверка: (13+3):(5+3) = 2;  2=2

в) брату  сейчас ----- 5 лет

брату год назад ----- в 3 раза <, чем сестре сейчас

сестре сейчас ---- ? лет

Решение.

5 - 1 = 4 (года) ---- было брату  год назад

4 * 3 = 12 (лет) --- сестре сейчас

Ответ: 12 лет

Проверка: 12 : (5-1) = 3  ;   3=3

г) условие, а значит, и решение,  одинаковое с в). Переписывать его считаю нецелесообразным. Возможно, нужно: "Сейчас брату 5 лет, а год назад ему было в 3 раза меньше лет, чем сестре (тогда же) Сколько лет сестре сейчас?" Тогда:

Решение

5 - 1 = 4 (года) ---- было брату год назад

4 * 3 = 12 (лет) --- было сестре года назад

12 + 1 = 13 (лет) ---- сестре сейчас.

Ответ: 13 лет.

Проверка : (5-1)*3 = 13 -1;   12 = 12

Answer 2

Question B:

To solve this problem, let's break it down step by step.

We know that the brother is currently 5 years old and in 3 years he will be half the age of his sister. Let's represent the sister's current age as x.

In 3 years, the brother will be 5 + 3 = 8 years old. According to the problem, he will be half the age of his sister at that time. So, we can set up the equation:

8 = (1/2) * (x + 3)

To solve for x, we can multiply both sides of the equation by 2:

16 = x + 3

Subtracting 3 from both sides, we get:

x = 13

Therefore, the sister is currently 13 years old.

Question в:

Let's solve this problem step by step.

We know that the brother is currently 5 years old and a year ago he was three times younger than his sister. Let's represent the sister's current age as x.

A year ago, the brother was 5 - 1 = 4 years old. According to the problem, he was three times younger than his sister at that time. So, we can set up the equation:

4 = 3 * (x - 1)

To solve for x, we can divide both sides of the equation by 3:

(x - 1) = 4 / 3

Adding 1 to both sides, we get:

x = 4 / 3 + 1

Simplifying the expression, we have:

x = 4 / 3 + 3 / 3

Combining the fractions, we get:

x = 7 / 3

Therefore, the sister is currently 7/3 years old, which is equivalent to 2 and 1/3 years old.

Question г:

Let's solve this problem step by step.

We know that the brother is currently 5 years old and a year ago he was three times younger than his sister. Let's represent the sister's current age as x.

A year ago, the brother was 5 - 1 = 4 years old. According to the problem, he was three times younger than his sister at that time. So, we can set up the equation:

4 = 3 * (x - 1)

To solve for x, we can divide both sides of the equation by 3:

(x - 1) = 4 / 3

Adding 1 to both sides, we get:

x = 4 / 3 + 1

Simplifying the expression, we have:

x = 4 / 3 + 3 / 3

Combining the fractions, we get:

x = 7 / 3

Therefore, the sister is currently 7/3 years old, which is equivalent to 2 and 1/3 years old.