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

[EX Q]: Sentence: 'seagulls sit on the posts of a seaside balcony by a clock tower'. Find frequency of the letter 'g'
[EX A]: 1

[EX Q]: Sentence: 'a double decker bus with a lot of people on board'. Find frequency of the letter 'l'
[EX A]: 3

[EX Q]: Sentence: 'a man doing skate board tricks at a skate park'. Find frequency of the letter 'd'
[EX A]:
2