Question

the age ofa& b re in ratio 5:7 four years form now the ratio of their ages will be 3:4 the present age of B is:- ?​

Answer 1

Let the present ages of A and B be 5x and 7x respectively.

After four years the ratio of their ages is 3:4

⟹
7x+4
5x+4
​
=
4
3
​

⟹20x+16=21x+12
⟹x=4

The present age of B is 7x=7×4=28years

Answer 2

Answer: Present Ratio of Age = 5 : 7

Four Year From Now = 3 : 4

Find Present Age of B.

Let the Present Age of A be 5n, and Present Age of B be 7n.

⇒ A + 4 years : B + 4 years = 3 : 4

⇒ (5n + 4) : (7n + 4) = 3 : 4

Product of Mean = Product of Extreme

⇒ 4 × (5n + 4) = (7n + 4) × 3

⇒ 20n + 16 = 21n + 12

⇒ 16 - 12 = 21n - 20n

⇒ n = 4

_______________________________

• PRESENT AGES WILL BE :

◗ A = 5n = 5(4) = 20 Years

◗ B = 7n = 7(4) = 28 Years

∴ Hence, Present Age of B is 28 Years.

Step-by-step explanation: