Answer:
The expression is 1 Australian dólar is equal to 0.67 US dollar 
Explanation:
To convert australian dollars to US dollar you have to use the currency Exchange that is the conversion rate between this 2 divises. 
Now, the currency Exchange is 
1 Australian dólar is equal to 0.67 US dollar 
So, 22 Australian dollars are 22*0.67= 14.74 US dollar