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

Example Input: Sentence: 'a close up of a grassy beach showing an umbrella and wind board'. Replace the letter 'a' with 'f' in the sentence.
Example Output: f close up of f grfssy befch showing fn umbrellf fnd wind bofrd

Example Input: Sentence: 'a woman sitting on a wooden chair holding a cat'. Replace the letter 'n' with 'q' in the sentence.
Example Output: a womaq sittiqg oq a woodeq chair holdiqg a cat

Example Input: Sentence: 'two tennis players play tennis on the court'. Replace the letter 'y' with 'b' in the sentence.
Example Output:
two tennis plabers plab tennis on the court