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

[EX Q]: Sentence: 'a man sitting on a motorcycle near two other men'. Find frequency of the letter 'r'
[EX A]: 3

[EX Q]: Sentence: 'a woman holds some baked goods at the convention'. Find frequency of the letter 'd'
[EX A]: 3

[EX Q]: Sentence: 'a couple of ducks are sitting in a cage'. Find frequency of the letter 'u'
[EX A]:
2