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

Example Input: Sentence: 'people watching a kite being flown with a sky background'. Replace the letter 'a' with 'b' in the sentence.
Example Output: people wbtching b kite being flown with b sky bbckground

Example Input: Sentence: 'horses drink and graze the field and water'. Replace the letter 'i' with 'c' in the sentence.
Example Output: horses drcnk and graze the fceld and water

Example Input: Sentence: 'a bathroom with a bath tub next to a sink'. Replace the letter 'o' with 'e' in the sentence.
Example Output:
a bathreem with a bath tub next te a sink