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

Example Input: Sentence: 'a young man playing tennis and preparing to hit the ball'. Replace the letter 'e' with 'c' in the sentence.
Example Output: a young man playing tcnnis and prcparing to hit thc ball

Example Input: Sentence: 'the bus is trying to navigate though the london traffic'. Replace the letter 'a' with 'l' in the sentence.
Example Output: the bus is trying to nlviglte though the london trlffic

Example Input: Sentence: 'little toddler in pajamas is using electric toothbrush'. Replace the letter 'r' with 'l' in the sentence.
Example Output:
little toddlel in pajamas is using electlic toothblush