Answer:
80
Step-by-step explanation:
Initial ratio:
Teachers to students
1 : 15
Ratio after:
Teachers to students
3 : 40
The number of students did not change, so we can make the students of the initial ratio and the students of the ratio after the same.
1 : 15 = 8 : 120
3 : 40 = 9 : 120
120 units = 1200
1 unit = 
Initial teachers = 8 units = 
Answer:
You want to solve for x, the first thing you need to do is distribute
The 2 through the x+4 then the other 2 through the -8-x
2(x+4)= 2x+8
2(-8-x)= -16-2x
2x+8=-16-2x-2x (combine like terms on the right side)
2x+8=-16-4x (now subtract 8 from each side)
2x=-24-4x (8-8=0, -16-8=-24) (now add 4x to each side)
6x=-24 (-4x+4x=0, 2x+4x=6x), (divide each side by 6)
x=-4 (6/6=1, -24/6=-4)
x=-4
Hope this helps ;)
