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

[EX Q]: Sentence: 'a picture of two computers on a table'. Find frequency of the letter 'r'
[EX A]: 2

[EX Q]: Sentence: 'a pizza is in a box on a table outside'. Find frequency of the letter 'u'
[EX A]: 1

[EX Q]: Sentence: 'two horses and a carriage being driven by a man in historical clothing'. Find frequency of the letter 't'
[EX A]:
3