Simplify the following text for a Grade 12 native English-speaking person.
Original: When the Count asks her to explain about the letter accusing the Countess of infidelity , Susanna and the Countess explain that the letter was written by Figaro , and then delivered through Basilio .
Simplified: When the Count presses about the anonymous letter , Susanna and the Countess reveal that the letter was written by Figaro , and then delivered through Basilio .