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

Sentence: 'two zebra stand near the wooden posts on a building'. Find frequency of the letter 't'
4

Sentence: 'pedestrian in stripe clothing standing on street corner'. Find frequency of the letter 's'
4

Sentence: 'a tan and green motorcycle grouped together with other motorcycles by a bike rack'. Find frequency of the letter 'e'

9