Business Math Questions

Durgesh is working in a restaurant in which he prepares two types of dishes $A$ and $B$. Dish $A$ takes 20 minutes to be prepared and Dish $B$ takes 30 minutes for the same. He earns Rs 50 to make one packet of dish $A$, while Rs 70 for one packet of dish $B$. He works for 12 hours a day, including 1 hour for personal activities. What will be the objective function if this example is formulated as a linear programming problem? Assume $x$ and $y$ are the packets of dishes $A$ and $B$ respectively.