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

Sentence: 'an image of a cautionary construction sign'. Find frequency of the letter 'a'
5

Sentence: 'a person is performing a stunt on a snowboard'. Find frequency of the letter 'p'
2

Sentence: 'the boy wearing the number 14 is getting ready to bat'. Find frequency of the letter 'u'

1