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

[EX Q]: Sentence: 'some people sitting on surfboards in the water'. Find frequency of the letter 't'
[EX A]: 4

[EX Q]: Sentence: 'a white toilet sitting next to a toilet paper roller'. Find frequency of the letter 'o'
[EX A]: 4

[EX Q]: Sentence: 'people watching a player at the plate during a little league game'. Find frequency of the letter 'e'
[EX A]:
9