Then there are 4x+78 students.

Now eight people are arranged at each intersection.

Then x- 1 intersection is 8(x- 1) people.

There are 4x+78-8(x- 1)=-4x+86 people.

so 4 < =-4x+86 & lt； eight

-82 & lt； =-4x & lt； =-78

Divide by -4

20.5 >= x & gt 19.5

So x=20.

4x+78= 158

So it's 20 intersections 158 students.