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

[Q]: Sentence: 'a man in his car eating a donut'. Find frequency of the letter 'm'
[A]: 1


[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: 'a woman is making donuts in a deep fryer'. Find frequency of the letter 'a'
[A]:
4