-5x(-3x+10)=30

Solution for -5x(-3x+10)=30 equation:

-5x(-3x+10)=30

We move all terms to the left:

-5x(-3x+10)-(30)=0

We multiply parentheses

15x^2-50x-30=0

a = 15; b = -50; c = -30;
Δ = b2-4ac
Δ = -502-4·15·(-30)
Δ = 4300
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{4300}=\sqrt{100*43}=\sqrt{100}*\sqrt{43}=10\sqrt{43}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-50)-10\sqrt{43}}{2*15}=\frac{50-10\sqrt{43}}{30}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-50)+10\sqrt{43}}{2*15}=\frac{50+10\sqrt{43}}{30}
$