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

[Q]: Sentence: 'the skateboarder has on red and black sneakers and is riding a skateboard'. Find frequency of the letter 'g'
[A]: 1

[Q]: Sentence: 'a plastic plastic plate topped with three different type of food'. Find frequency of the letter 'l'
[A]: 3

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