(5x-20)(6x-3)=0

Solution for (5x-20)(6x-3)=0 equation:

(5x-20)(6x-3)=0

We multiply parentheses ..

(+30x^2-15x-120x+60)=0

We get rid of parentheses

30x^2-15x-120x+60=0

We add all the numbers together, and all the variables

30x^2-135x+60=0

a = 30; b = -135; c = +60;
Δ = b2-4ac
Δ = -1352-4·30·60
Δ = 11025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{11025}=105$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-135)-105}{2*30}=\frac{30}{60}
=1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-135)+105}{2*30}=\frac{240}{60}
=4
$