-28x+80=-2x^2

Solution for -28x+80=-2x^2 equation:

-28x+80=-2x^2

We move all terms to the left:

-28x+80-(-2x^2)=0

We get rid of parentheses

2x^2-28x+80=0

a = 2; b = -28; c = +80;
Δ = b2-4ac
Δ = -282-4·2·80
Δ = 144
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{144}=12$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-28)-12}{2*2}=\frac{16}{4}
=4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-28)+12}{2*2}=\frac{40}{4}
=10
$