250=20x+6x^2

Solution for 250=20x+6x^2 equation:

250=20x+6x^2

We move all terms to the left:

250-(20x+6x^2)=0

We get rid of parentheses

-6x^2-20x+250=0

a = -6; b = -20; c = +250;
Δ = b2-4ac
Δ = -202-4·(-6)·250
Δ = 6400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{6400}=80$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-80}{2*-6}=\frac{-60}{-12}
=+5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+80}{2*-6}=\frac{100}{-12}
=-8+1/3
$