TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a group of people walking down a rain soaked street with umbrellas'. Find frequency of the letter 'w'

SOLUTION: 3

PROBLEM: Sentence: 'oranges are sitting in a bowl on a table'. Find frequency of the letter 'a'

SOLUTION: 5

PROBLEM: Sentence: 'a herd of zebra standing on top  of a grass covered field'. Find frequency of the letter 'e'

SOLUTION:
5