The mean of the ACT test scores is \( \mu = 21.0 \) and the deviations from the mean are:
- For score \( 22 \): \( 1.0 \)
- For score \( 25 \): \( 4.0 \)
- For score \( 18 \): \( -3.0 \)
- For score \( 20 \): \( -1.0 \)
- For score \( 20 \): \( -1.0 \)
Thus, the final answer is:
\[
\boxed{\text{Mean} = 21.0, \text{Deviations} = \{1.0, 4.0, -3.0, -1.0, -1.0\}}
\]