TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a young man with glasses on is taking a big bite'. Find frequency of the letter 's'

SOLUTION: 4

PROBLEM: Sentence: 'a knife a cutting board some bananas and a toaster'. Find frequency of the letter 'i'

SOLUTION: 2

PROBLEM: Sentence: 'the top door of a stainless steel refrigerator is standing open'. Find frequency of the letter 't'

SOLUTION:
6