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

Example Input: Sentence: 'a large orange cat sits in a chair outside'. Replace the letter 'e' with 'x' in the sentence.
Example Output: a largx orangx cat sits in a chair outsidx

Example Input: Sentence: 'the man is skiing fast in the snow'. Replace the letter 'o' with 'x' in the sentence.
Example Output: the man is skiing fast in the snxw

Example Input: Sentence: 'thirteen foot long hot dogs being served on a tray'. Replace the letter 'a' with 'g' in the sentence.
Example Output:
thirteen foot long hot dogs being served on g trgy