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

[Q]: Sentence: 'two men are playing a video game as another sits watching'. Find frequency of the letter 'a'
[A]: 7


[Q]: Sentence: 'a boy swinging a bat while playing baseball'. Find frequency of the letter 'h'
[A]: 1


[Q]: Sentence: 'a man hitting a tennis ball with a tennis racquet'. Find frequency of the letter 't'
[A]:
6