Roberto learns that his class grades correspond to a z score of 1.5 in psychology, a z score of 1.5 in music, and a z score of 1.5 in speech. Each class had a different mean. The mean in psychology was 82, the mean in music was 75, and the mean in speech was 90. How could he have the same z score in each class if the means are different? Can you determine his raw score in each class? Show your work.