-5y(-3y+10)=-20

Solution for -5y(-3y+10)=-20 equation:

-5y(-3y+10)=-20

We move all terms to the left:

-5y(-3y+10)-(-20)=0

We add all the numbers together, and all the variables

-5y(-3y+10)+20=0

We multiply parentheses

15y^2-50y+20=0

a = 15; b = -50; c = +20;
Δ = b2-4ac
Δ = -502-4·15·20
Δ = 1300
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:

$\sqrt{\Delta}=\sqrt{1300}=\sqrt{100*13}=\sqrt{100}*\sqrt{13}=10\sqrt{13}$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-50)-10\sqrt{13}}{2*15}=\frac{50-10\sqrt{13}}{30}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-50)+10\sqrt{13}}{2*15}=\frac{50+10\sqrt{13}}{30}
$