Final answer:
To find the number of students enrolled at Valley View Middle School before the increase, we need to subtract the increase from the total number of students after the increase. The correct answer is a) 700.
Step-by-step explanation:
To find the number of students enrolled at Valley View Middle School before the increase, we need to subtract the increase from the total number of students after the increase. We know that the enrollment increase was 10% and brought the total number of students to 770. Let's assume the number of students before the increase is x.
10% of x is 0.1x. So, the number of students after the increase is x + 0.1x = 1.1x.
From the given information, we have 1.1x = 770.
Dividing both sides of the equation by 1.1, we get x = 700.
Therefore, there were 700 students enrolled at Valley View Middle School before the increase. So, the correct answer is a) 700.