TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a woman at a table checking her cell phone'. Find frequency of the letter 'a'

SOLUTION: 5

PROBLEM: Sentence: 'a cat sleeping near lots of pairs of shoes'. Find frequency of the letter 'r'

SOLUTION: 2

PROBLEM: Sentence: 'a man riding a white surfboard on a large wave'. Find frequency of the letter 'a'

SOLUTION:
7