profit and loss

I got 1.1=4000
but if x=1.15
1.15x=4000
x=4000/1.15
x=3478

Let me see if I can break this out into some steps:

You know what the teacher's salary is after a 10% increase. What you need to solve for is the teacher's salary before the 10% increase. So the equation is set up like this:

(1.10)(x) = $4400, where x=teacher's salary before the 10% increase

Solving for x, you get x = $4000

Now the question asks for what the teacher's salary is after a 15% increase. At this point you know the original salary (solved above), so the equation looks like:

New Salary = (1.15)(4000)
New Salary = $4600

You used the equation 1.15x = $4000, which is saying that a 15% increase to the salary of x is $4000. You have your terms mixed up.

Easiest way to solve :
110% = 4400
=> 115% = (4400*115)/110 = 4600