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

[EX Q]: Sentence: 'a full plate of food that includes rice and broccoli and carrots'. Find frequency of the letter 's'
[EX A]: 2

[EX Q]: Sentence: 'a couple of boys in a field playing baseball'. Find frequency of the letter 'i'
[EX A]: 3

[EX Q]: Sentence: 'a woman on a beach by bags and a bicycle'. Find frequency of the letter 'n'
[EX A]:
3