Question

Отец в 3 раза старше сына и на 20 лет старше дочери. Сколько лет дочери,если всем вместе 100лет?С решением:)

Answer 1

Х  лет сыну
3Х лет отцу
(3Х-20) лет дочери
Х+3Х+(3Х-20)=100
7Х=100+20
7Х=120
Х=120:7
Х = 120/7 лет сыну
3*120/7 -20 = 360/7 - 140/7= 220/7 = 31 3/7  лет дочери

Answer 2

Problem Analysis

We are given that the father is three times older than the son and 20 years older than the daughter. We need to find the age of the daughter if the sum of their ages is 100.

Solution

Let's assume the age of the son is x years.

According to the given information, the father is three times older than the son, so the father's age is 3x years.

The father is also 20 years older than the daughter, so the daughter's age is x + 20 years.

The sum of their ages is 100, so we can write the equation:

x + 3x + (x + 20) = 100

Simplifying the equation:

5x + 20 = 100

Subtracting 20 from both sides:

5x = 80

Dividing both sides by 5:

x = 16

Therefore, the son is 16 years old.

To find the age of the daughter, we substitute the value of x into the equation:

x + 20 = 16 + 20 = 36

So, the daughter is 36 years old.

Answer

The daughter is 36 years old.

Explanation

According to the given information, the father is three times older than the son and 20 years older than the daughter. By solving the equation, we find that the son is 16 years old and the daughter is 36 years old.