0=279+72y-9y^2

Solution for 0=279+72y-9y^2 equation:

0=279+72y-9y^2

We move all terms to the left:

0-(279+72y-9y^2)=0

We add all the numbers together, and all the variables

-(279+72y-9y^2)=0

We get rid of parentheses

9y^2-72y-279=0

a = 9; b = -72; c = -279;
Δ = b2-4ac
Δ = -722-4·9·(-279)
Δ = 15228
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{15228}=\sqrt{324*47}=\sqrt{324}*\sqrt{47}=18\sqrt{47}$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-72)-18\sqrt{47}}{2*9}=\frac{72-18\sqrt{47}}{18}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-72)+18\sqrt{47}}{2*9}=\frac{72+18\sqrt{47}}{18}
$