Downside:

$$No margin:$$

$$Purchase $100$ shares @ $$50$ and sell them @ $$30$ in $1$ year.

$$Profit $=?$ & Return $=?$

$$Margin:

$$Purchase $200$ shares @ $$50$ by borrowing $$5000$ at $9\%.$

$$Sell $200$ shares @ $$30$ in $1$ year

$$Profit $=?$

$$Return $=?$