Mr. Lin is four times as old as his daughter. In 4 years he will be three times as old as his daughter. How she is his daughter now?

The present age of Mr. Lin's daughter = 8 years old.

The present age of Mr. Lin = 32 years old

Step-by-step explanation:

Let the present age of Mr. Lin's daughter = x yrs old

So, the present age of Mr. Lin = 4 times daughter's age = (4 x) yrs

Now, age of daughter after 4 years = (x + 4) yrs

and the age of Mr. Lin after 4 years = (4x + 4) years

Also, (4x + 4) = 3 times (x+4)

According to the question:

4x + 4 = 3 (x+4)

or, 4x + 4 = 3x + 12

⇒ 4x - 3x = 12 - 4

or, x = 8

Hence, the present age of Mr. Lin's daughter = 8 years old.

and the present age of Mr. Lin = 4 x = 4 x 8 = 32 years old