A is twice as old as B. Ten years ago, A was four times as old as B. What are their present ages?

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28 & 14

30 & 15

24 & 12

32 & 16

answer is B.

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Detailed Solution

Concept- Solution can be obtained by assuming the value of the required field to be x and
evaluating further. The concept of single variable linear equation balancing is used.
Given information:
Present Scenario,
A is twice as old as B
Ten years ago,
A was 4x as old as B.
So, as we have two conditions, we can form two equations
Let us assume that the current age of B = x years.
According to the question
A is twice as old as B.
We can say that, Age of
A=2×(Age of B)
Age of A=2x …….(i)
Now, from the second statement:
Ten years ago, A was four times as old as B.
As ten years ago,
Age of B=x−10
Age of A=2x−10
So, according to the statement Ten years ago, A was four times as old as B.
⇒ Age of A=4×(Age of B)
So, by putting values we get