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

[EX Q]: Sentence: 'a woman at a table checking her cell phone'. Find frequency of the letter 'a'
[EX A]: 5

[EX Q]: Sentence: 'two bears swim in a blue pool of water'. Find frequency of the letter 'o'
[EX A]: 4

[EX Q]: Sentence: 'slices of cake next to another desert on a plate'. Find frequency of the letter 'o'
[EX A]:
4