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

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


[Q]: Sentence: 'many white birds flying above a river that flows in front of a forest'. Find frequency of the letter 'a'
[A]: 5


[Q]: Sentence: 'a driver steers a tram onto a tangle of tracks'. Find frequency of the letter 'e'
[A]:
4