40=24x-2x^2

Solution for 40=24x-2x^2 equation:

40=24x-2x^2

We move all terms to the left:

40-(24x-2x^2)=0

We get rid of parentheses

2x^2-24x+40=0

a = 2; b = -24; c = +40;
Δ = b2-4ac
Δ = -242-4·2·40
Δ = 256
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{256}=16$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-24)-16}{2*2}=\frac{8}{4}
=2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-24)+16}{2*2}=\frac{40}{4}
=10
$