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 guy surfs a wave with his surfboard'. Find frequency of the letter 's'
answer:
4


question:
Sentence: 'a bowl filled with hot dogs next to a bowl of chili'. Find frequency of the letter 'l'
answer:

5