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

Sentence: 'a softball player holding the bat on first base'. Find frequency of the letter 't'
4

Sentence: 'three elephants walk up a dirt trail from the water'. Find frequency of the letter 'l'
3

Sentence: 'half of a bus with stickers all over it'. Find frequency of the letter 'h'
2