TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'two persons standing outside a moving sub train'. Find frequency of the letter 'a'

SOLUTION: 3

PROBLEM: Sentence: 'a silver train crossing the road on tracks'. Find frequency of the letter 'r'

SOLUTION: 5

PROBLEM: Sentence: 'a large grou is standing near a table with condiments, paper plates, and an open box'. Find frequency of the letter 'a'

SOLUTION:
10