instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a street at night with trees and streetlights on'. Find frequency of the letter 't'
answer:
9


question:
Sentence: 'some sheep are standing in a grassy field'. Find frequency of the letter 'n'
answer:
3


question:
Sentence: 'a couple of zebras start to cross a dirt road'. Find frequency of the letter 'l'
answer:

1