TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'a couple of giraffe standing next to each other'. Replace the letter 'i' with 'q' in the sentence.

SOLUTION: a couple of gqraffe standqng next to each other

PROBLEM: Sentence: 'a bathroom with a white toilet next to a large window'. Replace the letter 'w' with 'x' in the sentence.

SOLUTION: a bathroom xith a xhite toilet next to a large xindox

PROBLEM: Sentence: 'three blue and white airplanes are on an airport runway'. Replace the letter 'u' with 't' in the sentence.

SOLUTION:
three blte and white airplanes are on an airport rtnway