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

Sentence: 'supplies and tools are arranged on the floor with a hard hat and bag'. Find frequency of the letter 'n'
4

Sentence: 'an image of a cautionary construction sign'. Find frequency of the letter 'a'
5

Sentence: 'a train, resembling a red passenger bus, is on the tracks outside the station'. Find frequency of the letter 's'

8