Erica and Nina began arguing about who did better on their tests, but they couldn't decide who did better given that they took different tests. Erica took a test in Social Studies and earned a 80.5, and Nina took a test in Art History and earned a 61.1. Use the fact that all the students' test grades in the Social Studies class had a mean of 73.9 and a standard deviation of 10.6, and all the students' test grades in Art History had a mean of 63.2 and a standard deviation of 8.7 to answer the following questions.

Calculate the z-score for Erica's test grade.

Calculate the z-score for Nina's test grade.