TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'some sheep are standing in a grassy field'. Find frequency of the letter 'n'

SOLUTION: 3

PROBLEM: Sentence: 'two people under an umbrella while walking down a sidewalk'. Find frequency of the letter 'i'

SOLUTION: 3

PROBLEM: Sentence: 'slices of beef with vegetables and brown gravy'. Find frequency of the letter 'g'

SOLUTION:
2