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

[EX Q]: Sentence: 'a herd of horses standing next to each other on a field'. Find frequency of the letter 'r'
[EX A]: 3

[EX Q]: Sentence: 'a room with a big screen television and a couch'. Find frequency of the letter 'h'
[EX A]: 2

[EX Q]: Sentence: 'a man prepares to through a frisbee while another man watches'. Find frequency of the letter 'r'
[EX A]:
5