instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'there is a person standing on a blue towel'. Find frequency of the letter 'n'
answer:
4

question:
Sentence: 'a railroad train pulling up to the train platform'. Find frequency of the letter 'o'
answer:
3

question:
Sentence: 'a mostly white living room with colorful books on a shelf'. Find frequency of the letter 'b'
answer:
1