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 small boy in a high chair eating a cupcake'. Find frequency of the letter 'i'
4

Sentence: 'a pile of broccoli sitting beside a knife'. Find frequency of the letter 'i'

6