(3y-25)(y+15)=180

Solution for (3y-25)(y+15)=180 equation:

(3y-25)(y+15)=180

We move all terms to the left:

(3y-25)(y+15)-(180)=0

We multiply parentheses ..

(+3y^2+45y-25y-375)-180=0

We get rid of parentheses

3y^2+45y-25y-375-180=0

We add all the numbers together, and all the variables

3y^2+20y-555=0

a = 3; b = 20; c = -555;
Δ = b2-4ac
Δ = 202-4·3·(-555)
Δ = 7060
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:

$\sqrt{\Delta}=\sqrt{7060}=\sqrt{4*1765}=\sqrt{4}*\sqrt{1765}=2\sqrt{1765}$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(20)-2\sqrt{1765}}{2*3}=\frac{-20-2\sqrt{1765}}{6}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20)+2\sqrt{1765}}{2*3}=\frac{-20+2\sqrt{1765}}{6}
$