Question

Suppose there are two monuments. Monument A is thrice as old as
monument B. After 12 years, monument A will be twice as old as monument B.
How many years have passed since the construction of each monument?

Answer 1

Answer :-

$\longrightarrow$ The age of Monument A is 36 years.

$\longrightarrow$ The age of Monument B is 12 years.

Solution :-

Let the age of Monument A be A and the age of Monument B be B.

Case - I :

Given that Monument A is thrice as old as  monument B, i.e.

=> A = 3B   ....i.)

Case - II :

Given that after 12 years, monument A will be twice as old as monument B, i.e.,

Age of Monument A after 12 years = A + 12

Age of Monument B after 12 years = B+ 12

=> A + 12 = 2(B + 12)

=> A + 12 = 2B + 24

=> A = 2B + 24 - 12

=> A = 2B + 12

Substituting the value of A from equation i.)

=> 3B = 2B+ 12

=> 3B - 2B =  12

=> B = 12

Now, finding A by substituting the value of B

=> A = 3B

=> A = 3 × 12

=> A = 36

$\longrightarrow$ The age of Monument A is 36 years.

$\longrightarrow$ The age of Monument B is 12 years.