Question

The number of boys and girls in the class is in the ratio 5:7. Four years later, the sum of their ages will be 56 years. What are their present ages. ​

Answer 1

Required Answer :

Present age of boys = 20 years

Present age of girls = 28 years

Given :

• Ratio of the number of boys and girls in the class = 5 : 7

• The sum of their ages, after 4 years = 56 years

To find :

• The present ages of boys and girls

Solution :

Let :-

• Present age of boys = 5x years
• Present age of girls = 7x years

Their ages after 4 years :-

→ Age of boys = 5x + 4 years

→ Age of girls = 7x + 4 years

According to the question,

→ Age of boys + Age of girls = 56

→ 5x + 4 + 7x + 4 = 56

→ 12x + 8 = 56

→ 12x = 56 - 8

→ 12x = 48

→ x = 48/12

→ x = 4

Substituting the value of 'x' :-

→ Present age of boys = 5x

→ Present age of boys = 5(4)

→ Present age of boys = 20 years

→ Present age of girls = 7x

→ Present age of girls = 7(4)

→ Present age of girls = 28 years

Answer 2

❍Given:

• The number of boys and girls in the class is in the ratio 5:7.
• Four years later, the sum of their ages will be 56 years.

❍To Find:

• Present Ages

❍Solution:

Let,

• Present ages of boy = 5y
• Present Ages of girl = 7y

Four years later,

• Boy's age = 5y + 4
• Girl's age = 7y + 4

According to Question:

➠ (5y + 4) + (7y + 4) = 56

➠ 12y + 8 = 56

➠ 12y = 56 - 8

➠ 12y = 48

➠ y = 48/12

➠ y = 4 years

Present age of boys = 5y

• Present age of boys = 5 × 4
• Present age of boys = 20 years

Present age of girls = 7y

• Present age of girls = 7 × 4
• Present age of girls = 28 years