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

[EX Q]: Sentence: 'a view from a bathroom shows an open door'. Find frequency of the letter 'o'
[EX A]: 7

[EX Q]: Sentence: 'a group of men standing on the side of a boat'. Find frequency of the letter 'o'
[EX A]: 5

[EX Q]: Sentence: 'the bright blue background makes the street sign easy to read'. Find frequency of the letter 'y'
[EX A]:
1