Question

the age of harish and mary are in the ratio 5:7.Four years from now the ratio of their ages will be 3:4.Find their present age.​

Answer 1

Given :-

• The age of Harish and Mary are in the ratio 5:7.Four years from now the ratio of their ages will be 3:4.

To find :-

• Present ages

Solution :-

The age of Harish and mary are in the ratio 5:7.

• Let the age of Harish be 5x and Mary be 7x

→ After four years

• Harish's age = 5x + 4
• Mary's age = 7x + 4

Four years from now the ratio of their ages will be 3:4.

According to the given condition

→ 5x + 4/7x + 4 = 3/4

→ 4(5x + 4) = 3(7x + 4)

→ 20x + 16 = 21x + 12

→ 16 - 12 = 21x - 20x

→ 4 = x

→ x = 4

Hence,

• Present age of Harish = 5x = 20 years

• Present age of Mary = 7x = 28 years

Answer 2

Given : The age of Harish and Mary are in the ratio 5:7. Four years from now the ratio of their ages will be 3:4.

　

To find : What is their present age?

　

☯ Solution :

• Let us assume "x" as the common ratio between their ages.

　

• Let "5x" be Harish's age and "7x" be Mary's age.

　

• Let "5x + 4" be age of Harish after four years and "7x + 4" be age of Mary after four years.

　

Calculations :

$:\implies\sf{\dfrac{5x + 4}{7x + 4} = \dfrac{3}{4}}$

　

$:\implies\sf{4 (5x + 4) = 3 (7x + 4)}$

　

$:\implies{\underline{\boxed{\sf{x = 4 \: years}}}}$

　

Substuting the above value :

$:\implies\sf{5x = (5 \times 4)}$

　

$:\implies{\underline{\boxed{\sf{5x = 20 \: years}}}}$

　

　

$:\implies\sf{7x = (7 \times 4)}$

　

$:\implies{\underline{\boxed{\sf{7x = 28 \: years}}}}$

　

Therefore, 20 and 28 are their present ages respectively.