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

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

Sentence: 'a full plate of food that includes rice and broccoli and carrots'. Find frequency of the letter 's'
2

Sentence: 'a man riding on top of a rail with a snowboard'. Find frequency of the letter 'n'

4