Final answer:
The ratio of 6th graders to 7th graders in Mr. Fisher's class is 6:5 after simplifying the initial ratio of 30:25 by dividing both numbers by the greatest common divisor of 5.
Step-by-step explanation:
The question asks for the ratio of 6th graders to 7th graders in Mr. Fisher's P.E. class. There are 30 6th graders and 25 7th graders. To find the ratio, we divide the number of 6th graders by the number of 7th graders. So, the ratio of 6th graders to 7th graders is 30:25. This can be further simplified by dividing both numbers by their greatest common divisor (GCD), which in this case is 5. Therefore, the simplified ratio is 6:5.