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

Example Input: Sentence: 'a person and a dog are on a bench'. Replace the letter 'e' with 'r' in the sentence.
Example Output: a prrson and a dog arr on a brnch

Example Input: Sentence: 'a couple of giraffes being feed by people at the zoo'. Replace the letter 't' with 'v' in the sentence.
Example Output: a couple of giraffes being feed by people av vhe zoo

Example Input: Sentence: 'elephants' skin looks muddy due to wallowing in the water'. Replace the letter 'g' with 'q' in the sentence.
Example Output:
elephants' skin looks muddy due to wallowinq in the water