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

Example Input: Sentence: 'a laptop computer attached to a large monitor'. Replace the letter 'a' with 'r' in the sentence.
Example Output: r lrptop computer rttrched to r lrrge monitor

Example Input: Sentence: 'a group of people on a beach flying a kite'. Replace the letter 'p' with 'i' in the sentence.
Example Output: a groui of ieoile on a beach flying a kite

Example Input: Sentence: 'two ends of train cars, one is handicap accessible'. Replace the letter 't' with 'h' in the sentence.
Example Output:
hwo ends of hrain cars, one is handicap accessible