Question

the ages of Sonu and Monu are in the ratio 7:5.Ten years hence,the ratio of their ages will be 9:7.Find their present ages.

Answer 1

let the ages of Sonu and monu be 7x and 5x respectively and after ten yrs there ages will be 9x and 7x respectively
according to question
(7x+10)/(5x+10) = 9x/7x
(7x+10)/(5x+10) = 9/7
7(7x+10) = 9(5x+10)
49x+70 = 45x +90
4x = 20 => x = 20/4 = 5 yrs
sonu's age = 7x = 7×5 = 35 yrs
monu's age = 5x = 5×5 = 25yrs

hope this helps

Answer 2

Let us assume the present age of Sonu to be 7a years.

Let us assume the present age of Monu to be 5a years.

Calculating Sonu's age after 10 years:

(7a+ 10) Years

Calculating Monu's age after 10 years:

(5a + 10) Years

The ratio of their ages after 10 years given to us = 9/7

According to question:

(7a+ 10) / (5a + 10) = 9/7

Cross multiplying this equation:

=> 7(7a + 10) = 9(5a + 10)

=> 49a + 70 = 45a + 90

Taking 45 to the other side of the equation we get:

=> 49a - 45a = - 70 + 90

=> 4a = 20

Taking 4 to the other side of the equation we get:

=> a = 20 / 4

=> a = 5

Calculating the present age of Sonu:

= 7a

= 7 x 5

= 35

Therefore, the present age of Sonu is 35 years.

Calculating the present age of Monu:

= 5a

= 5 x 5

= 25

Therefore, the present age of Monu is 25 years.