(5x-5)(4x-1)=0

Solution for (5x-5)(4x-1)=0 equation:

(5x-5)(4x-1)=0

We multiply parentheses ..

(+20x^2-5x-20x+5)=0

We get rid of parentheses

20x^2-5x-20x+5=0

We add all the numbers together, and all the variables

20x^2-25x+5=0

a = 20; b = -25; c = +5;
Δ = b2-4ac
Δ = -252-4·20·5
Δ = 225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{225}=15$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-25)-15}{2*20}=\frac{10}{40}
=1/4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-25)+15}{2*20}=\frac{40}{40}
=1
$