In this task, you need to count the number of times the given letter appears in the given sentence.

Sentence: 'a glass bowl of raw broccoli, a ceramic bowl of raw green chili peppers, and steel bowl of raw daikon'. Find frequency of the letter 'a'
9

Sentence: 'a person standing operating a cell phone in a room'. Find frequency of the letter 'n'
6

Sentence: 'close up view of an adult colorful parrot'. Find frequency of the letter 'u'

3