Suppose that $ a + b = 20$, $b + c = 22$, and $c + a = 2022$. Compute $\frac{a-b}{c-a}$ .
1. We are given the equations:
   \[
   a + b = 20
   \]
   \[
   b + c = 22
   \]
   \[
   c + a = 2022
   \]

2. To find \(a - b\), we subtract the second equation from the third equation:
   \[
   (c + a) - (b + c) = 2022 - 22
   \]
   Simplifying, we get:
   \[
   a - b = 2000
   \]

3. Next, to find \(c - a\), we subtract the first equation from the second equation:
   \[
   (b + c) - (a + b) = 22 - 20
   \]
   Simplifying, we get:
   \[
   c - a = 2
   \]

4. Now, we need to compute \(\frac{a - b}{c - a}\):
   \[
   \frac{a - b}{c - a} = \frac{2000}{2} = 1000
   \]

The final answer is \(\boxed{1000}\).