Z = (60 - 70) / 10
Z = -1.0

Her Z-score is negative and below the mean.

More things to know about the Z-Score:

1. The Z-score can be positive or negative.
   Positive is above the mean.
   Negative is below the mean.
   
   
2. The mean of the Z-scores is always zero.
   If you got the class average on a test - your Z-score = 0. Because Z would be (mean score mean)/SD = 0.
   
   
3. The SD of the Z distribution = 1. We will discuss this later.