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

[EX Q]: Sentence: 'a man and several white red and blue airplanes'. Find frequency of the letter 'u'
[EX A]: 1

[EX Q]: Sentence: 'a white bowl filled with peeled orange slices'. Find frequency of the letter 's'
[EX A]: 2

[EX Q]: Sentence: 'a bed next to a desk with binoculars, book and lamp'. Find frequency of the letter 's'
[EX A]:
2