instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a little boy that has a toothbrush in his mouth'. Find frequency of the letter 'r'
answer:
1


question:
Sentence: 'three men in military suits are sitting on a bench,'. Find frequency of the letter 'a'
answer:
3


question:
Sentence: 'a dog is standing on his hind legs looking out the window on a screen door'. Find frequency of the letter 'd'
answer:

5