b^2-180b=90

Solution for b^2-180b=90 equation:

b^2-180b=90

We move all terms to the left:

b^2-180b-(90)=0

a = 1; b = -180; c = -90;
Δ = b2-4ac
Δ = -1802-4·1·(-90)
Δ = 32760
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{32760}=\sqrt{36*910}=\sqrt{36}*\sqrt{910}=6\sqrt{910}$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-180)-6\sqrt{910}}{2*1}=\frac{180-6\sqrt{910}}{2}
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-180)+6\sqrt{910}}{2*1}=\frac{180+6\sqrt{910}}{2}
$