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

[EX Q]: Sentence: 'a red stop sign with street signs above it'. Find frequency of the letter 't'
[EX A]: 5

[EX Q]: Sentence: 'the small black and white dog holds onto a frisbee'. Find frequency of the letter 'h'
[EX A]: 3

[EX Q]: Sentence: 'an hawaiian air plane is currently parked'. Find frequency of the letter 'u'
[EX A]:
1