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

[EX Q]: Sentence: 'a little boy that has a toothbrush in his mouth'. Find frequency of the letter 'r'
[EX A]: 1

[EX Q]: Sentence: 'a cat sprawls out and sleeps on its back on a lounge chair with an acorn theme'. Find frequency of the letter 'r'
[EX A]: 3

[EX Q]: Sentence: 'four people playing a doubles tennis match on  a red court'. Find frequency of the letter 'g'
[EX A]:
1