(80-y)(-y)=0

Solution for (80-y)(-y)=0 equation:

(80-y)(-y)=0

We add all the numbers together, and all the variables

(-1y+80)(-1y)=0

We multiply parentheses ..

(+y^2-80y)=0

We get rid of parentheses

y^2-80y=0

a = 1; b = -80; c = 0;
Δ = b2-4ac
Δ = -802-4·1·0
Δ = 6400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{6400}=80$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-80)-80}{2*1}=\frac{0}{2}
=0
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-80)+80}{2*1}=\frac{160}{2}
=80
$