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

[Q]: Sentence: 'a white and blue plate topped with meat and a salad'. Find frequency of the letter 'u'
[A]: 1


[Q]: Sentence: 'a bed with a mattress that has nothing on it'. Find frequency of the letter 'a'
[A]: 5


[Q]: Sentence: 'a street with six different motorcycles parked on the side of the street and trees in a park behind the bikes'. Find frequency of the letter 's'
[A]:
7