The annual returns of three stocks are given below.

Two of them $($Air America and Air Brazil$)$ are airline stocks

and one $($Star Oil$)$ is an oil stock.

In general, when oil prices go up$,$ airline company stocks go

down and oil company stocks go up$.$

Create a portfolio $($to diversify risk$)$ by mixing $50\%$ of Air

America and $50\%$ of Star Oil stocks.

How much is the portfolio's annual return?

Notice that annual return is the same for portfolio and