TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'an image of a cautionary construction sign'. Find frequency of the letter 'a'

SOLUTION: 5

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

SOLUTION: 2

PROBLEM: Sentence: 'three surfers walking along the beach after a swim'. Find frequency of the letter 'f'

SOLUTION:
2