Answer: Sell short the stock because it is overpriced.
Explanation:
To find out if the stock is overpriced or underpriced, you would need to check to see if the Expected return is indeed 12%.
With the given variables you can do this with the Capital Asset Pricing Model.
The formula is,
Er = Rf + b(Rm + Rf)
Where,
Er is the expected return
Rf is the Risk free rate
b is the Beta
Rm is the Market Rate
Inserting the figures,
= 7% + 1.3(15% - 7%)
= 17.4%
The stock should have an expected return of 17.4% but only has an expected return of 12%. It is underperforming and is therefore OVERPRICED. To benefit from this you should sell the stock short so that when the market prices adjust you can make a profit.