0.16=0.8x-x^2

Solution for 0.16=0.8x-x^2 equation:

0.16=0.8x-x^2

We move all terms to the left:

0.16-(0.8x-x^2)=0

We get rid of parentheses

x^2-0.8x+0.16=0

a = 1; b = -0.8; c = +0.16;
Δ = b2-4ac
Δ = -0.82-4·1·0.16
Δ = 1.11022302463E-16
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-0.8)-\sqrt{1.11022302463E-16}}{2*1}=\frac{0.8-\sqrt{1.11022302463E-16}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.8)+\sqrt{1.11022302463E-16}}{2*1}=\frac{0.8+\sqrt{1.11022302463E-16}}{2}
$