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

[EX Q]: Sentence: 'a man and a woman are walking down the street with an umbrella over their heads'. Find frequency of the letter 'w'
[EX A]: 4

[EX Q]: Sentence: 'a bird outside standing on a table looking up'. Find frequency of the letter 'b'
[EX A]: 2

[EX Q]: Sentence: 'birds flying over a sandy beach and landing on a platform'. Find frequency of the letter 'b'
[EX A]:
2