Question

can i have some examples of formal letters

Answer 1

Relative clauses are the clauses which explains the noun and you can identify them easily. If any clause is starting with some relative pronouns like ‘who’, ‘where’, ‘which’, ‘that’ and ‘whose’ are actually your relative clauses. The other name of the relative clause is an adjective or subordinate clause. 
Examples are,
1. She is the lady who is very kind.
2. He gave me a gift which I don’t like.