TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a man riding on the back of a white horse next to other horses'. Find frequency of the letter 'o'

SOLUTION: 6

PROBLEM: Sentence: 'slices of orange are arranged on a plate'. Find frequency of the letter 's'

SOLUTION: 2

PROBLEM: Sentence: 'two elephants in the field close to some building structures'. Find frequency of the letter 'i'

SOLUTION:
4