In order to meet the teacher's goal of scoring above 85%, we need to consider the students who scored above 85% and the students who scored exactly 85%.
From the given information, we know that:
15 students scored above 90%.
8 students scored between 85% and 90%.
Therefore, we can conclude that at least 15 + 8 = 23 students scored above or equal to 85%. However, this count includes the students who scored above 90%, so we need to subtract the number of students who scored above 90% to get the number of students who scored between 85% and 90%.
23 - 15 = 8
Hence, we have 8 students who scored between 85% and 90%.
Now, let's add the students who scored above 90% (15) and the students who scored between 85% and 90% (8):
15 + 8 = 23
Therefore, a total of 23 students scored above or equal to 85%.
Since the question specifically asks for the number of students who met the teacher's goal, we can select option 23 as the correct answer.