0=0.3x-0.003x^2

Solution for 0=0.3x-0.003x^2 equation:

0=0.3x-0.003x^2

We move all terms to the left:

0-(0.3x-0.003x^2)=0

We add all the numbers together, and all the variables

-(0.3x-0.003x^2)=0

We get rid of parentheses

0.003x^2-0.3x=0

a = 0.003; b = -0.3; c = 0;
Δ = b2-4ac
Δ = -0.32-4·0.003·0
Δ = 0.09
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-0.3)-\sqrt{0.09}}{2*0.003}=\frac{0.3-\sqrt{0.09}}{0.006}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.3)+\sqrt{0.09}}{2*0.003}=\frac{0.3+\sqrt{0.09}}{0.006}
$