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

Sentence: 'a black animal in dirt area below trees and rocks'. Find frequency of the letter 'n'
3

Sentence: 'a bird outside standing on a table looking up'. Find frequency of the letter 'b'
2

Sentence: 'an ipod is charging on a desk with the ear buds laying close by'. Find frequency of the letter 'e'

4