Factor 3x^3y^6-81 no clue man

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.)

Acomputer store bought a program at a cost of $10 and sold it for $13. find the percent markup

[tex]5 \times1 \frac{12}{13} [/tex] me