396400=6400x-18x^2-400

Solution for 396400=6400x-18x^2-400 equation:

396400=6400x-18x^2-400

We move all terms to the left:

396400-(6400x-18x^2-400)=0

We get rid of parentheses

18x^2-6400x+400+396400=0

We add all the numbers together, and all the variables

18x^2-6400x+396800=0

a = 18; b = -6400; c = +396800;
Δ = b2-4ac
Δ = -64002-4·18·396800
Δ = 12390400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{12390400}=3520$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-6400)-3520}{2*18}=\frac{2880}{36}
=80
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6400)+3520}{2*18}=\frac{9920}{36}
=275+5/9
$