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

Sentence: 'a man on a skateboard going down a ramp while people are watching'. Find frequency of the letter 'w'
3

Sentence: 'a woman holds the reins of a saddled horse'. Find frequency of the letter 'm'
1

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

3