Harsh was four times as old as Dev six years ago. How old is Dev today if Harsh will be 40 years old 10 years later?

Correct option is B

Given:

Harsh will be 40 years old 10 years later → Current age of Harsh = 40 − 10 = 30 years

Six years ago, Harsh was 4 times as old as Dev

Solution:
Let Dev's present age = x
Then 6 years ago:
Harsh's age = 30 − 6 = 24
Dev's age = x − 6

Given: 24 = 4(x − 6)

$$\Rightarrow$$​ 24 = 4x − 24

$$\Rightarrow$$​4x = 48

$$\Rightarrow$$​ x = 12

So, Dev's present age is 12 years

Thus, the correct option is (b) 12 years

Alternate Method:

Let present age of  Harsh  and Deve is H and D respectively:

Given : H + 10  = 40, then H = 30 years

According to the question:

H - 6 = 4 (D - 6)

Putting H = 30

30 - 6 = 4 D - 24

24 = 4 D - 24

4 D = 48

D = 12 years.

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