Let x represent the number of US dollars required. From the information given,
1.2 Australian dollars equals one us dollar
Thus,
22 Australian dollars = x US dollars
We would have the following equations
1.2 = 1
22 = x
By crossmultiplying, we have
x * 1.2 = 1 * 22
1.2x = 22
Dividing both sides of the equation by 1.2, we have
1.2x/1.2x = 22/1.2
The expression that can be used to convert 22 Australian dollars to US dollars is
x = 22/1.2