instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a bus is driving on the street behind some cars'. Find frequency of the letter 'a'
answer:
2


question:
Sentence: 'a woman with short, brown hair is looking into a circular mirror and holding a camera up to her cheek'. Find frequency of the letter 'e'
answer:
4


question:
Sentence: 'there is a young boy that is cutting a birthday cake'. Find frequency of the letter 't'
answer:

6