TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a girl laying on a bed posing for a picture'. Find frequency of the letter 'i'

SOLUTION: 4

PROBLEM: Sentence: 'a train sits on a railroad track as a metal awning covers it'. Find frequency of the letter 'l'

SOLUTION: 2

PROBLEM: Sentence: 'a cat has a surprised look as it sits on the top of a bookshelf with books on the first and second shelf'. Find frequency of the letter 'a'

SOLUTION:
7