Find the optimal solution. The Chris Beehner Company manufactures two lines of designer yard gates, called model A and model B$.$ Every gate requires blending a certain amount of steel and zinc; the company has available a total of $25,000$ lb of steel and $6,000$ lb of zinc. Each model A gate requires a mixture of $125$ lb of steel and $20$ lb of zinc, and each yields a profit of $ $65.$ Each model B gate requires $100$ lb of steel and $30$ lb of zinc and can be sold for a profit of $ $55.$