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

Sentence: 'some food on plates next to each other on a table'. Find frequency of the letter 'e'
6

Sentence: 'a picture of two computers on a table'. Find frequency of the letter 'r'
2

Sentence: 'a bearded male tennis player striking a tennis ball'. Find frequency of the letter 'r'

3