How do i solve for x using this pythagorean theorem ?

In a graph with several intervals o data how does a constant interval appear? what type of scenario produces a constant interval?

This is about circle theorems. someone asap : (

The number of 8th graders who responded to a poll of 6th grade and 8 th graders was one fourtg of the number of 6th graders whi responded if a total of 100 students responddd to the poll how many of the students responded were 6 th graders