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

Sentence: 'a bunch of green bananas is hanging on a tree'. Find frequency of the letter 'n'
7

Sentence: 'a herd of horses standing next to each other on a field'. Find frequency of the letter 'r'
3

Sentence: 'a surfer with his board heading towards the water'. Find frequency of the letter 'h'

4