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

[EX Q]: Sentence: 'a train sits on a railroad track as a metal awning covers it'. Find frequency of the letter 'l'
[EX A]: 2

[EX Q]: Sentence: 'a man standing on a tennis court holding a racquet'. Find frequency of the letter 's'
[EX A]: 2

[EX Q]: Sentence: 'oranges and a leaf are in a silver colander'. Find frequency of the letter 'r'
[EX A]:
4