Question

The ratio of 'a' and 'b' 3:1, after 15 years their ratio would be 2:1,
then what are their present ages?
O(a) 30,10
(b) 45,15
O(c) 21,7
(d) 60,20​

Answer 1

Answer:

b

Step-by-step explanation:

a:b=3:1

a=3x

b=x

a=3b

a+15 : b+15 = 2:1

a+15=2y

b+15=y

a+15=2(b+15)

a+15=2b+30

substitute a=3b in above equation

3b+15=2b+30

b=15

a=45

hope this helps

Answer 2

Given :-

The ratio of 'a' and 'b' is 3:1, after 15 years their ratio would be 2:1.

To Find :-

Present ages of a and b.

Answer :-

• Option b) 45, 15 is the correct answer.

Explaination :-

Let the present age's of 'a' and 'b' be 3x and x.

★ After 15 years

Age of 'a' = 3x + 15

Age of 'b' = x + 15

★ According to Question now :-

⇢ (3x + 15)/x + 15 = 2/1

by Cross multiplying both sides we get :

⇢ 1(3x + 15) = 2(x + 15)

⇢ 3x + 15 = 2x + 30

Combine like terms :

⇢ 3x - 2x = 30 - 15

⇢ x = 15

Hence,

• Present Age of a = 3x = 3(15) = 45 years
• Present Age of b = x = 15 years

Therefore, Option b) 45,15 is the correct answer.