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

Sentence: 'a woman holds some baked goods at the convention'. Find frequency of the letter 'd'
3

Sentence: 'there is no image here to provide a caption for'. Find frequency of the letter 'o'
5

Sentence: 'man in a black shirt is skating down the railing'. Find frequency of the letter 'n'
5