First, we need to know the units they used. For every hectare, there are 2.47105 acres.
 Next, we can set up a proportion to solve.
 

 Now, we will cross-multiply:
 $8,963 * 2.47105 = x
 x ≈ $22,148
 I was $10 from the answer they ended up with, so I most likely used a different conversion unit factor than they did. However, the steps are still the same.