TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a person is riding in a cart pulled by a horse'. Find frequency of the letter 'a'

SOLUTION: 4

PROBLEM: Sentence: 'four men standing around two pizzas in a conference room'. Find frequency of the letter 't'

SOLUTION: 2

PROBLEM: Sentence: 'a bird on a tree is flapping its wings'. Find frequency of the letter 'o'

SOLUTION:
1