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

Sentence: 'a downhill skier with snow plumes behind them'. Find frequency of the letter 'i'
4

Sentence: 'a man in a suit makes the first slice into a cake'. Find frequency of the letter 't'
4

Sentence: 'that looks like a huge jump on the snow'. Find frequency of the letter 's'

2