i can't  understand example 3

(i) Diganta's age is 2 years more than 4 times Arjun's age.

In these kinds of problems, first of all we have to choose a  variable.

In this problem we choose the variable Arjun, age, because Diganta's age depends on Arjun's age.

Let the age of Arjun be x years.

Now to find, Diganta's age, first we have to find the 4 times of Arjun's age and then adding 2 in it.

∴ 4 Times of Arjun, age = (4 × x) years = 4x years

Adding 2 in R.H.S

⇒(4x + 2) years, which is the age of Diganta.

(ii) In this problem we choose the variable breadth, because the length of rectangular field depends on the breadth of the rectangular field.

Let the breath of rectangular field =  x m

In order to find, length, first we have to find twice of breadth and then subtract 3 from it.

∴ Twice of breadth = (2 × x) m = 2x m

Subtracting 3 from R.H.S

⇒ (2x – 3)m, which is the length of rectangular field.

Try solving remaining parts of the problem yourself.

Cheers!