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

[EX Q]: Sentence: 'people playing wii bowling in a modern library'. Find frequency of the letter 'o'
[EX A]: 3

[EX Q]: Sentence: 'a glass a rope and a pair of scissors'. Find frequency of the letter 's'
[EX A]: 6

[EX Q]: Sentence: 'a hot dog with mustard and onions sitting on a tray'. Find frequency of the letter 't'
[EX A]:
6