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

Sentence: 'a white bathroom sink sitting next to a toilet'. Find frequency of the letter 'i'
5

Sentence: 'a tower with some bright lights and clocks on it'. Find frequency of the letter 'h'
3

Sentence: 'a picture of a machine built next to a street'. Find frequency of the letter 'x'

1