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:

Let present age of a be x years and b be years.

\frac{x}{y} = \frac{5}{7} \\ 7x - 5y = 0......1

\frac{x + 4}{y + 4} = \frac{3}{4} \\ 4x + 16 = 3y + 12 \\ 4x - 3y = - 4.....2

multiplying 1 with -3

- 21x + 15y = 0....3

multiplying 2 with 5

20x - 15y = - 20......4

adding 3 and 4

- x = - 20 \\ x = 20

put x=20 in 1

7 \times 20 - 5y = 0 \\ - 5y = - 140 \\ y = \frac{ - 140}{ - 5} \\ y = 28

therefore the present age of b 28 years

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Answer 2

Answer:

Present age of Nidhi =  20 Years

Present age of Paridhi = 28 Years

Step-by-step explanation:

Let the

Present Age of Nidhi = 5x

Present Age of Paridhi - 7x

After Four Years

Age of Nidhi = 5x + 4

Age of Paridhi = 7x + 4

Also its given that

$\frac{5x+4}{7x+4} = \frac{3}{4}$

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

ie 20x + 16 = 21x + 12

16-12 = 21x-20x

ie 4 = x

Therefore

Present age of Nidhi = 5 X 4 = 20 Years

Present age of Paridhi = 7 x 4 = 28 Years