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

Sentence: 'a view from a bathroom shows an open door'. Find frequency of the letter 'o'
7

Sentence: 'a very big nice looking living room with nice furnishings'. Find frequency of the letter 'e'
3

Sentence: 'a black and white photo of a boardwalk at night'. Find frequency of the letter 'h'
3