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

Sentence: 'two computers and a laptop set up on a desk'. Find frequency of the letter 'r'
1

Sentence: 'two people under an umbrella while walking down a sidewalk'. Find frequency of the letter 'i'
3

Sentence: 'the contents of a purse spread out on a table'. Find frequency of the letter 'e'

5