-15c^2=-30c

Solution for -15c^2=-30c equation:

-15c^2=-30c

We move all terms to the left:

-15c^2-(-30c)=0

We get rid of parentheses

-15c^2+30c=0

a = -15; b = 30; c = 0;
Δ = b2-4ac
Δ = 302-4·(-15)·0
Δ = 900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{900}=30$
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(30)-30}{2*-15}=\frac{-60}{-30}
=+2
$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(30)+30}{2*-15}=\frac{0}{-30}
=0
$