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

[Q]: Sentence: 'two people wearing snowboards sitting on a snowy slope'. Find frequency of the letter 's'
[A]: 5

[Q]: Sentence: 'a toilet of some sort near a sink of some sort'. Find frequency of the letter 'o'
[A]: 7

[Q]: Sentence: 'plates of chicken and vegetable, a plate with bread and a bowl of soup'. Find frequency of the letter 'a'
[A]:
8