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

Example Input: Sentence: 'a man walking his dog near a sandy area'. Replace the letter 'i' with 'g' in the sentence.
Example Output: a man walkgng hgs dog near a sandy area

Example Input: Sentence: 'a group of young people playing a game of soccer'. Replace the letter 'c' with 'o' in the sentence.
Example Output: a group of young people playing a game of soooer

Example Input: Sentence: 'a yellow and green fire hydrogen  that is next to a road'. Replace the letter 'y' with 't' in the sentence.
Example Output:
a tellow and green fire htdrogen  that is next to a road