Question

The ages of A and B are in the ratio of 5: 7 four years from now the ratio of their ages will be 3 : 4 The persent age of B is ​

Answer 1

Answer:

Let the common ratio of their ages be x

Let the Hari's age be 5x and Harry's age be 7x

Five years later:-

Hari's age=5x+4

Harry's age=7x+4

According to question....

5x+5 = 3

7x+5    4

By cross-multiplication,We get,

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

20x+20=21x+15

20-15=21x-20x

5=x

x=5

Present age of Hari=5x=5×5=25 years

Present age of Harry=7x=7×5=35 years

Step-by-step explanation:

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Answer 2

Answer:

The present age of $\rm{A}$ is $\rm{20\:years}$ and the present age of $\rm{B}$ is $\rm{28\:years}$

Step-by-step explanation:

→ Ratio given = $\rm{5 : 7}$

→ Let the age of $\rm{A}$ = $\rm{5x}$

→ Let the age of $\rm{B}$ = $\rm{7x}$

❖ Four years from now :

→ Age of $\rm{A}$ = $\rm{5x + 4}$

→ Age of $\rm{B}$ = $\rm{7x + 4}$

→ Ratio of their ages will be = $\rm{3 : 4}$

❖ According to the question :

→ $\rm{\dfrac{5x + 4}{7x + 4} = \dfrac{3}{4}}$

• By cross - multiplication :-

→ $\rm{4(5x + 4) = 3(7x + 4)}$

→ $\rm{20x + 16 = 21x + 12}$

→ $\rm{20x - 21x = 12 - 16}$

→ $\rm{\cancel{-} x = \cancel{-} 4}$

→ $\boxed{\rm x = 4}$

❖ Their ages :

• A's age = $\rm{5x = 5(4) = 20\ years}$
• B's age = $\rm{7x = 7(4) = 28\ years}$

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