Question

Лена в 3 раза моложе брата Саши,а вместе им 20 лет. Сколько лет Саше?Сколько лет Лене?

Answer 1

х лет Лене

3х лет Саше

х+3х=20

4х=20

х=5 лет Лене

5*3=15 лет Саше

Answer 2

Пусть Лене х лет, а Саше у лет, тогда

3х = у(1)

и

х + у = 20 (2)

Подставим (1) в (2)

х + 3х = 20

4х = 20

х = 5

у = 3*5 = 15

Ответ: Лене 5 лет, Саше 15 лет

 

Answer 3

Problem Analysis

We are given that Lena is three times younger than her brother Sasha, and their ages sum up to 20 years. We need to determine the ages of Sasha and Lena.

Solution

Let's assume Sasha's age is x years. According to the given information, Lena's age would be (1/3)x years.

We are also given that the sum of their ages is 20 years. We can set up the following equation:

x + (1/3)x = 20

Simplifying the equation:

(4/3)x = 20

To solve for x, we can multiply both sides of the equation by 3/4:

x = (20 * 3/4) = 15

Therefore, Sasha is 15 years old.

To find Lena's age, we can substitute the value of x into the expression (1/3)x:

Lena's age = (1/3) * 15 = 5

Therefore, Lena is 5 years old.

Answer

Sasha is 15 years old and Lena is 5 years old.