1 US dollar is equal to 1.2857 Australian dollars.
Explanation:
Step 1:
Assume 1 Canadian dollar is equal to x, 1 US dollar is equal to y and 1 Australian dollar is equal to z.
It is given that 5 Canadian dollars are worth 4 US dollars. So
take this as equation 1.
It is also given that 9 Australian dollars are worth 7 US dollars. So
take this as equation 2.
Step 2:
We need to determine how much z is equal to 1y.
To do so, we use equation 2 and solve for z while y has a coefficient of 1.
So 1 US dollar is equal to 1.2857 Australian dollars.