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 crowd of fans watch soccer players from stadium seating'. Find frequency of the letter 'f'
3

Sentence: 'a plane with smoke coming from the tips of both wings'. Find frequency of the letter 'c'

1