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

Sentence: 'a bird outside standing on a table looking up'. Find frequency of the letter 'b'
2

Sentence: 'man in red shirt with black suitcase standing outside of building'. Find frequency of the letter 'i'
8

Sentence: 'a woman in brown jacket throwing a yellow frisbee'. Find frequency of the letter 'i'

3