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

[EX Q]: Sentence: 'a downhill skier with snow plumes behind them'. Find frequency of the letter 'i'
[EX A]: 4

[EX Q]: Sentence: 'a man with glasses adjusting his tie in a mirror'. Find frequency of the letter 's'
[EX A]: 5

[EX Q]: Sentence: 'a cat waiting to be served at the kitchen table'. Find frequency of the letter 't'
[EX A]:
7