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

[EX Q]: Sentence: 'a woman is playing an interactive video game'. Find frequency of the letter 't'
[EX A]: 2

[EX Q]: Sentence: 'the large modern train is on the train track'. Find frequency of the letter 'm'
[EX A]: 1

[EX Q]: Sentence: 'a yellow train coming down a train track'. Find frequency of the letter 'k'
[EX A]:
1