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

Sentence: 'a blue train on a track next to another track'. Find frequency of the letter 'c'
2

Sentence: 'a person does a trick on a ramp on a snowboard'. Find frequency of the letter 's'
3

Sentence: 'lamps in different shapes and colors lite up in the dusk'. Find frequency of the letter 'o'

2