In this task, you need to count the number of times the given letter appears in the given sentence.

Sentence: 'a doorway looking into a small bathroom with white toilet'. Find frequency of the letter 'r'
2

Sentence: 'a plastic tray that has different foods inside of it'. Find frequency of the letter 't'
6

Sentence: 'a cow being held by its harness in a open field'. Find frequency of the letter 'g'

1