How do I solve this. plz help What is the answer?

If the measure of xyz is 81 what is the measure of yz

Arestaurant offers a $12 dinner special that has 5 choices for an appetizer, 12 choices for an entrée, and 4 choices for a dessert. how many different meals are available when you select an appetizer, an entrée, and a dessert? a meal can be chosen in nothing ways. (type a whole number.)

Linda loans her friend $250 with a 5% monthly intrest rate. how much was the whole loan?