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

[EX Q]: Sentence: 'man in air skateboarding on street with building'. Find frequency of the letter 't'
[EX A]: 4

[EX Q]: Sentence: 'a car accident has slowed traffic as a clean up crew works'. Find frequency of the letter 'f'
[EX A]: 2

[EX Q]: Sentence: '3 giraffes and 3 zebras in an exhibit'. Find frequency of the letter 'a'
[EX A]:
4