Given that Manish is three years younger than Nitish. so, Manish's age is always three years less than Nitish's age. [1 mark]
For example,
If Nitish’s age is 12 years, his brother’s age would be 12 - 3 = 9 years.
So, if Nitish’s age is x, then the expression for Manish’s age would be (x−3). [1 mark]