instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a train station with a train pulling into the platform'. Find frequency of the letter 'i'
answer:
6


question:
Sentence: 'a train on a train track going through a bunch of trees'. Find frequency of the letter 'u'
answer:
2


question:
Sentence: 'a plate topped with a hamburger and hot dog'. Find frequency of the letter 'h'
answer:

3