Question

the ages of Nidhi and paridhi are in the ratio of 5:7 four years from now the ratio of their ages will be 3:4 find their present age​

Answer 1

ANSWER
The ratio of Hari's and Harry's present ages is 5:7

So, let their ages be 5x and 7x

After 4 years their ages will be in ratio 3:4

Therefore,(5x+4)/(7x+4)=3/4

or, 4(5x+4)=3(7x+4)

or, 20x+16=21x+12

or, 16−12=21x−20x

or, 4=1x

or, x=4

Therefore, present age of Hari = 5x=(5×4)=20 years.
Present age of Harry =7x=(7×4)=28 years
The sum of their age is 28+20=48years

Answer 2

Let the ages of Nidhi be 5x and that of Paridhi be 7x

After 4 years

3:4

Nidhi = 5x + 4

Paridhi = 7x  + 4

$5x + 4/ 7x + 4 = 3/4$

3(7x + 4) = 4(5x + 4)

21x  + 12 = 20x + 16

21x - 20x = 16-12

x = 4

Therefore Nidhi's age = 4 X 5 = 20years

Paridhi's age = 4 X 7 = 28 years

Hope it helps