TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'a cat is watching a computer with a video of a cat'. Replace the letter 't' with 'a' in the sentence.

SOLUTION: a caa is waaching a compuaer wiah a video of a caa

PROBLEM: Sentence: 'a metal tray holding various vegetables that include potatoes and onions'. Replace the letter 'h' with 'e' in the sentence.

SOLUTION: a metal tray eolding various vegetables teat include potatoes and onions

PROBLEM: Sentence: 'a girl wearing white shorts walks across train tracks while holding an umbrella above herself'. Replace the letter 'h' with 'f' in the sentence.

SOLUTION:
a girl wearing wfite sforts walks across train tracks wfile folding an umbrella above ferself