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: 'this is a sign in front of a large cathedral'. Find frequency of the letter 'a'
answer:
5


question:
Sentence: 'an image of two zebras side by side'. Find frequency of the letter 'a'
answer:

3