In this task, you need to replace a letter in the sentence with another given letter.

Example Input: Sentence: 'three young school girls waiting on a subway train platform'. Replace the letter 't' with 'o' in the sentence.
Example Output: ohree young school girls waioing on a subway orain plaoform

Example Input: Sentence: 'a man in blazer holding a tie over his eyes'. Replace the letter 's' with 'e' in the sentence.
Example Output: a man in blazer holding a tie over hie eyee

Example Input: Sentence: 'an asian kid is riding his skateboard and doing some tricks in the air'. Replace the letter 'm' with 'b' in the sentence.
Example Output:
an asian kid is riding his skateboard and doing sobe tricks in the air