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

Sentence: 'a crowd of people standing in front of a green train'. Find frequency of the letter 'g'
2

Sentence: 'a man in costume talking on a cell phone'. Find frequency of the letter 'm'
2

Sentence: 'a bicycle chained to a rail near a flooded area'. Find frequency of the letter 'c'

3