In this task, you need to count the number of times the given letter appears in the given sentence.

[Q]: Sentence: 'people waiting on a train platform in a wooded area'. Find frequency of the letter 'p'
[A]: 3

[Q]: Sentence: 'the receipts from a meal at a restaurant are for a sandwich, chili, and apple'. Find frequency of the letter 'u'
[A]: 1

[Q]: Sentence: 'group in darklit room talking and looking at their cell phones holding wine glasses'. Find frequency of the letter 'i'
[A]:
7