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

[EX Q]: Sentence: 'a line of people on motorcycles on the road'. Find frequency of the letter 'e'
[EX A]: 5

[EX Q]: Sentence: 'a girl that has a kite in the air'. Find frequency of the letter 'r'
[EX A]: 2

[EX Q]: Sentence: 'a kitchen with large wooden cabinets next to a sink'. Find frequency of the letter 'k'
[EX A]:
2