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

[Q]: Sentence: 'a man flying through the air on top of a skateboard'. Find frequency of the letter 'r'
[A]: 3


[Q]: Sentence: 'a little child looking up to a camera holding a cell phone'. Find frequency of the letter 'g'
[A]: 2


[Q]: Sentence: 'couple of people just exited the bus and is walking through parking lot'. Find frequency of the letter 'w'
[A]:
1