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

Sentence: 'a stop sign and a red fire hydrant grass cars and trees'. Replace the letter 'd' with 's' in the sentence.

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
a stop sign ans a res fire hysrant grass cars ans trees