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

Sentence: 'a double decker bus with a lot of people on board'. Find frequency of the letter 'l'
3

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

Sentence: 'two people are riding on canoes down a river'. Find frequency of the letter 'e'

5