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

Sentence: 'this is a sign in front of a large cathedral'. Find frequency of the letter 'a'
5

Sentence: 'a white bowl filled with peeled orange slices'. Find frequency of the letter 's'
2

Sentence: 'this is a short person running with a checkerboard kite'. Find frequency of the letter 'c'

2