180=(4x+20)(x-10)

Solution for 180=(4x+20)(x-10) equation:

180=(4x+20)(x-10)

We move all terms to the left:

180-((4x+20)(x-10))=0

We multiply parentheses ..

-((+4x^2-40x+20x-200))+180=0


We calculate terms in parentheses: -((+4x^2-40x+20x-200)), so:

(+4x^2-40x+20x-200)

We get rid of parentheses

4x^2-40x+20x-200

We add all the numbers together, and all the variables

4x^2-20x-200

Back to the equation:

-(4x^2-20x-200)


We get rid of parentheses

-4x^2+20x+200+180=0

We add all the numbers together, and all the variables

-4x^2+20x+380=0

a = -4; b = 20; c = +380;
Δ = b2-4ac
Δ = 202-4·(-4)·380
Δ = 6480
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{6480}=\sqrt{1296*5}=\sqrt{1296}*\sqrt{5}=36\sqrt{5}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(20)-36\sqrt{5}}{2*-4}=\frac{-20-36\sqrt{5}}{-8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20)+36\sqrt{5}}{2*-4}=\frac{-20+36\sqrt{5}}{-8}
$