Create a system of equations
x + y = 123
5x + y = 343
I use substitution
y = 123 - x
5x + 123 - x = 343
4x + 123 = 343
4x = 220
x = 55
Plug in
x + y = 123
55 + y = 123
y = 68
Check
5x + y = 343
5(55) + 68 = 343
275 + 68 = 343
343 = 343
Seeing where the x and y diffreant on the line :)
There would be 2034 students competing in 2012.
We can write a simple equation to find this answer. Let X, be the number of students starting in 2012. Then, we multiply by 0.9 and 1.1 to get to 2014. To work backwards, just divide by 1.1, then by 0.9.
2014 / 1.1 / 0.9 = 2034
