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

Sentence: 'a double parking meter is decorated with a picture of a girl with wings on her feet'. Find frequency of the letter 'r'
6

Sentence: 'a yellow fire hydrant in the forefront of a roadway'. Find frequency of the letter 'r'
5

Sentence: 'passengers are walking alongside a yellow train inside of a station'. Find frequency of the letter 'r'

3