(80-2y)y=768

Solution for (80-2y)y=768 equation:

(80-2y)y=768

We move all terms to the left:

(80-2y)y-(768)=0

We add all the numbers together, and all the variables

(-2y+80)y-768=0

We multiply parentheses

-2y^2+80y-768=0

a = -2; b = 80; c = -768;
Δ = b2-4ac
Δ = 802-4·(-2)·(-768)
Δ = 256
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{256}=16$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(80)-16}{2*-2}=\frac{-96}{-4}
=+24
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(80)+16}{2*-2}=\frac{-64}{-4}
=+16
$