We need to find the expression that represents the average of three test scores
At first : the average = the sum of the data over the number of the data
We have 3 test scores : x , y and z
The sum of the scores = x + y + z
The number of the scores = 3
so, the average will be :
![(x+y+z)/(3)](https://img.qammunity.org/2023/formulas/mathematics/college/hoyuymvjypwg6kf5x0re46kqf6xa4q2k5n.png)
So, the answer is : ( x + y+ z )/3