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 dog has found a rather large stick for playing fetch'. Find frequency of the letter 't'
3

Sentence: 'a guy riding a bike close to a car in the street'. Find frequency of the letter 'i'

4