3600=-20x^2+560x

Solution for 3600=-20x^2+560x equation:

3600=-20x^2+560x

We move all terms to the left:

3600-(-20x^2+560x)=0

We get rid of parentheses

20x^2-560x+3600=0

a = 20; b = -560; c = +3600;
Δ = b2-4ac
Δ = -5602-4·20·3600
Δ = 25600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{25600}=160$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-560)-160}{2*20}=\frac{400}{40}
=10
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-560)+160}{2*20}=\frac{720}{40}
=18
$