instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a young boy bouncing a tennis ball on a tennis racquet'. Find frequency of the letter 'a'
answer:
5


question:
Sentence: 'city two way street with cars lined up on both sides'. Find frequency of the letter 'h'
answer:
2


question:
Sentence: 'a train is moving over a train bridge'. Find frequency of the letter 'd'
answer:

1