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

[EX Q]: Sentence: 'the counter of a doctor's office, including a laptop, cotton swabs, and tongue depressors'. Find frequency of the letter 'g'
[EX A]: 2

[EX Q]: Sentence: 'young girl playing with refrigerator magnet while kneeling on floor'. Find frequency of the letter 'n'
[EX A]: 6

[EX Q]: Sentence: 'tattered and soiled toy bear on a city sidewalk at night'. Find frequency of the letter 'b'
[EX A]:
1