0=24x-0.4x^2

Solution for 0=24x-0.4x^2 equation:

0=24x-0.4x^2

We move all terms to the left:

0-(24x-0.4x^2)=0

We add all the numbers together, and all the variables

-(24x-0.4x^2)=0

We get rid of parentheses

0.4x^2-24x=0

a = 0.4; b = -24; c = 0;
Δ = b2-4ac
Δ = -242-4·0.4·0
Δ = 576
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{576}=24$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-24)-24}{2*0.4}=\frac{0}{0.8}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-24)+24}{2*0.4}=\frac{48}{0.8}
=60
$