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

[EX Q]: Sentence: 'a red fire hydrant opened and spilling water'. Find frequency of the letter 'd'
[EX A]: 4

[EX Q]: Sentence: 'the small black and white dog holds onto a frisbee'. Find frequency of the letter 'h'
[EX A]: 3

[EX Q]: Sentence: 'eight donuts are cooked together in oil in a metal tray'. Find frequency of the letter 'h'
[EX A]:
2