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

Sentence: 'a pizza is in a box on a table outside'. Find frequency of the letter 'u'
1

Sentence: 'a tall building with antenna stands before a jet flying in the background'. Find frequency of the letter 't'
6

Sentence: 'some red white yellow and blue buses and some buildings'. Find frequency of the letter 'e'
7