-5x^2+85x=-90

Solution for -5x^2+85x=-90 equation:

-5x^2+85x=-90

We move all terms to the left:

-5x^2+85x-(-90)=0

We add all the numbers together, and all the variables

-5x^2+85x+90=0

a = -5; b = 85; c = +90;
Δ = b2-4ac
Δ = 852-4·(-5)·90
Δ = 9025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9025}=95$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(85)-95}{2*-5}=\frac{-180}{-10}
=+18
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(85)+95}{2*-5}=\frac{10}{-10}
=-1
$