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

Sentence: 'vanity sitting atop a base with two doors and a mirror overhead'. Find frequency of the letter 'n'
3

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 bed is lit by two light on each side'. Find frequency of the letter 's'

2