30=(10-2x)(8-2x)

Solution for 30=(10-2x)(8-2x) equation:

30=(10-2x)(8-2x)

We move all terms to the left:

30-((10-2x)(8-2x))=0

We add all the numbers together, and all the variables

-((-2x+10)(-2x+8))+30=0

We multiply parentheses ..

-((+4x^2-16x-20x+80))+30=0


We calculate terms in parentheses: -((+4x^2-16x-20x+80)), so:

(+4x^2-16x-20x+80)

We get rid of parentheses

4x^2-16x-20x+80

We add all the numbers together, and all the variables

4x^2-36x+80

Back to the equation:

-(4x^2-36x+80)


We get rid of parentheses

-4x^2+36x-80+30=0

We add all the numbers together, and all the variables

-4x^2+36x-50=0

a = -4; b = 36; c = -50;
Δ = b2-4ac
Δ = 362-4·(-4)·(-50)
Δ = 496
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:

$\sqrt{\Delta}=\sqrt{496}=\sqrt{16*31}=\sqrt{16}*\sqrt{31}=4\sqrt{31}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(36)-4\sqrt{31}}{2*-4}=\frac{-36-4\sqrt{31}}{-8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(36)+4\sqrt{31}}{2*-4}=\frac{-36+4\sqrt{31}}{-8}
$