800=240x-16x^2

Solution for 800=240x-16x^2 equation:

800=240x-16x^2

We move all terms to the left:

800-(240x-16x^2)=0

We get rid of parentheses

16x^2-240x+800=0

a = 16; b = -240; c = +800;
Δ = b2-4ac
Δ = -2402-4·16·800
Δ = 6400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{6400}=80$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-240)-80}{2*16}=\frac{160}{32}
=5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-240)+80}{2*16}=\frac{320}{32}
=10
$