instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a railroad train pulling up to the train platform'. Find frequency of the letter 'o'
answer:
3


question:
Sentence: 'a train is sitting at a train station'. Find frequency of the letter 'r'
answer:
2


question:
Sentence: 'two skateboarders going fast down an empty road'. Find frequency of the letter 'm'
answer:

1


