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

Sentence: 'a blue and white train is coming down some tracks'. Replace the letter 'b' with 'u' in the sentence.
a ulue and white train is coming down some tracks

Sentence: 'a clean, sterile bathroom with a shower, toilet, and sink'. Replace the letter 'n' with 'k' in the sentence.
a cleak, sterile bathroom with a shower, toilet, akd sikk

Sentence: 'a man on a horse in riding gear looking onward'. Replace the letter 'o' with 'h' in the sentence.

a man hn a hhrse in riding gear lhhking hnward