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

Example Input: Sentence: 'a man is standing at the base ball triangle with bat in tow'. Replace the letter 'n' with 'c' in the sentence.
Example Output: a mac is stacdicg at the base ball triacgle with bat ic tow

Example Input: Sentence: 'a man is at bat at a baseball game with a crowd watching'. Replace the letter 't' with 'f' in the sentence.
Example Output: a man is af baf af a baseball game wifh a crowd wafching

Example Input: Sentence: 'there is no image on this page to describe'. Replace the letter 'r' with 'v' in the sentence.
Example Output:
theve is no image on this page to descvibe