TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'an commercial airline airplane flies above the clouds'. Find frequency of the letter 'n'

SOLUTION: 3

PROBLEM: Sentence: 'a dog has found a rather large stick for playing fetch'. Find frequency of the letter 't'

SOLUTION: 3

PROBLEM: Sentence: 'a group of dogs that are standing in a kitchen'. Find frequency of the letter 't'

SOLUTION:
4