The current monetary policy is in favour of a strong dollar and we anticipate a bearish move on the AUD/USD.
We decide to go short 1 lot (100,000 units) of AUD/USD at a price of 0.73700. The margin required to open the position will be (using 400:1 leverage):
100,000 x 0.73700 / 400 = 184.25 USD
After some time the market moves in our direction, and is now trading at 0.73200.
We decide to take our profits and close the position.
The profit made on this position will be:
0.73700 - 0.73200 = 50 pips.
1 lot = 10 USD per pip.
Therefore, the total profit we made is 50 x 10 = 500 USD.