0=100-40x+3x^2

Solution for 0=100-40x+3x^2 equation:

0=100-40x+3x^2

We move all terms to the left:

0-(100-40x+3x^2)=0

We add all the numbers together, and all the variables

-(100-40x+3x^2)=0

We get rid of parentheses

-3x^2+40x-100=0

a = -3; b = 40; c = -100;
Δ = b2-4ac
Δ = 402-4·(-3)·(-100)
Δ = 400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{400}=20$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(40)-20}{2*-3}=\frac{-60}{-6}
=+10
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(40)+20}{2*-3}=\frac{-20}{-6}
=3+1/3
$