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

Example Input: Sentence: 'a couch, footrest, tv and other furniture are arranged in a living room'. Replace the letter 'o' with 'g' in the sentence.
Example Output: a cguch, fggtrest, tv and gther furniture are arranged in a living rggm

Example Input: Sentence: 'a guy looking at a tennis ball with a goofy look'. Replace the letter 'a' with 'x' in the sentence.
Example Output: x guy looking xt x tennis bxll with x goofy look

Example Input: Sentence: 'three different types of dogs looking at the camera'. Replace the letter 'r' with 'q' in the sentence.
Example Output:
thqee diffeqent types of dogs looking at the cameqa