0=-5x^2+80x+195

Solution for 0=-5x^2+80x+195 equation:

0=-5x^2+80x+195

We move all terms to the left:

0-(-5x^2+80x+195)=0

We add all the numbers together, and all the variables

-(-5x^2+80x+195)=0

We get rid of parentheses

5x^2-80x-195=0

a = 5; b = -80; c = -195;
Δ = b2-4ac
Δ = -802-4·5·(-195)
Δ = 10300
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{10300}=\sqrt{100*103}=\sqrt{100}*\sqrt{103}=10\sqrt{103}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-80)-10\sqrt{103}}{2*5}=\frac{80-10\sqrt{103}}{10}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-80)+10\sqrt{103}}{2*5}=\frac{80+10\sqrt{103}}{10}
$