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

Sentence: 'a plastic container next to a toilet on a wooden box'. Find frequency of the letter 'i'
3

Sentence: 'a white police vehicle parked on a paved street'. Find frequency of the letter 'a'
4

Sentence: 'a person is holding a half eaten donut'. Find frequency of the letter 'p'

1