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

[Q]: Sentence: 'a man with headphones on is hunched over a sink while being recorded'. Find frequency of the letter 'd'
[A]: 4


[Q]: Sentence: 'a passenger train that is going over a bridge'. Find frequency of the letter 't'
[A]: 3


[Q]: Sentence: 'the skateboarder has on red and black sneakers and is riding a skateboard'. Find frequency of the letter 'g'
[A]:
1