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

[Q]: Sentence: 'three young children playing with a ball in front of a huge bridge'. Find frequency of the letter 'e'
[A]: 5

[Q]: Sentence: 'a player swings his bat at a baseball game'. Find frequency of the letter 'p'
[A]: 1

[Q]: Sentence: 'closed toilet and simple shower in a home bathroom'. Find frequency of the letter 'd'
[A]:
2