(4t-20)(20t-4)=0

Solution for (4t-20)(20t-4)=0 equation:

(4t-20)(20t-4)=0

We multiply parentheses ..

(+80t^2-16t-400t+80)=0

We get rid of parentheses

80t^2-16t-400t+80=0

We add all the numbers together, and all the variables

80t^2-416t+80=0

a = 80; b = -416; c = +80;
Δ = b2-4ac
Δ = -4162-4·80·80
Δ = 147456
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{147456}=384$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-416)-384}{2*80}=\frac{32}{160}
=1/5
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-416)+384}{2*80}=\frac{800}{160}
=5
$