(300-w)w=21600

Solution for (300-w)w=21600 equation:

(300-w)w=21600

We move all terms to the left:

(300-w)w-(21600)=0

We add all the numbers together, and all the variables

(-1w+300)w-21600=0

We multiply parentheses

-1w^2+300w-21600=0

a = -1; b = 300; c = -21600;
Δ = b2-4ac
Δ = 3002-4·(-1)·(-21600)
Δ = 3600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$w_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$w_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3600}=60$
$w_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(300)-60}{2*-1}=\frac{-360}{-2}
=+180
$
$w_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(300)+60}{2*-1}=\frac{-240}{-2}
=+120
$