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

[EX Q]: Sentence: 'a couple of girls are hanging out at a restaurant'. Find frequency of the letter 'l'
[EX A]: 2

[EX Q]: Sentence: 'a very big nice looking living room with nice furnishings'. Find frequency of the letter 'e'
[EX A]: 3

[EX Q]: Sentence: 'a cat sitting on a window sill near a window'. Find frequency of the letter 't'
[EX A]:
3