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

[Q]: Sentence: 'group of cars on the road with the sun setting behind it'. Find frequency of the letter 'd'
[A]: 2

[Q]: Sentence: 'a woman walking with a child that is in a wheelchair'. Find frequency of the letter 'k'
[A]: 1

[Q]: Sentence: 'a cat sitting on top of a refrigerator freezer'. Find frequency of the letter 'n'
[A]:
2