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 group of people are using their laptops in the dark'. Replace the letter 'p' with 'b' in the sentence.
a groub of beoble are using their labtobs in the dark

Sentence: 'a person loading a bite of cake onto a fork'. Replace the letter 'r' with 'd' in the sentence.

a pedson loading a bite of cake onto a fodk