Question

I want to write the letter to my mother ask for money to pay for the trip

Answer 1

as you are writing a letter to your mother it means that the form of the letter is informal and the method to write informal letters is

sender's address ( means your address)

date,day

receiver's address ( means your mother's)

salutations (dear)

body of the letter

subscription (thanking you).

your name...

so this is the method.
now can you write the letter.
hope its helpful to you