(4x-20)(3x)=180

Solution for (4x-20)(3x)=180 equation:

(4x-20)(3x)=180

We move all terms to the left:

(4x-20)(3x)-(180)=0

We multiply parentheses

12x^2-60x-180=0

a = 12; b = -60; c = -180;
Δ = b2-4ac
Δ = -602-4·12·(-180)
Δ = 12240
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:

$\sqrt{\Delta}=\sqrt{12240}=\sqrt{144*85}=\sqrt{144}*\sqrt{85}=12\sqrt{85}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-60)-12\sqrt{85}}{2*12}=\frac{60-12\sqrt{85}}{24}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-60)+12\sqrt{85}}{2*12}=\frac{60+12\sqrt{85}}{24}
$