Why do Minerva and Trujillo roll the dice? Why does Trujillo propose to play?8

In Trujillo's office, it is revealed that Tio Chiche, one of Trujillo's friends, is related to Chea Mirabal. He is a gambler and Mama doesn't like him very much, but she jumps on this connection in order to appeal to Trujillo. Minerva notices a set of dice on Trujillo's desk, and she realizes that they are loaded. She makes a bet with him: they will roll the dice, and if she wins, she can go to law school, but if he wins, he gets to sleep with her. Minerva knows to use the heavier set of dice, and of course she wins, to Trujillo's annoyance. Minerva, Chea, and Enrique Mirabal drive home in the rain.