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

[EX Q]: Sentence: 'two young ladies that are dancing in the room together'. Find frequency of the letter 'a'
[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: 'three people standing next to a bus that has its door open'. Find frequency of the letter 'e'
[EX A]:
6