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

Sentence: 'a woman walking on a shore next to a river'. Find frequency of the letter 'v'
1

Sentence: 'a man hitting a tennis ball with a tennis racquet'. Find frequency of the letter 't'
6

Sentence: 'a group of young women eating pizza together'. Find frequency of the letter 'r'

2