120=0.2c^2

Solution for 120=0.2c^2 equation:

120=0.2c^2

We move all terms to the left:

120-(0.2c^2)=0

We get rid of parentheses

-0.2c^2+120=0

a = -0.2; b = 0; c = +120;
Δ = b2-4ac
Δ = 02-4·(-0.2)·120
Δ = 96
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{96}=\sqrt{16*6}=\sqrt{16}*\sqrt{6}=4\sqrt{6}$
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-4\sqrt{6}}{2*-0.2}=\frac{0-4\sqrt{6}}{-0.4}
=-\frac{4\sqrt{6}}{-0.4}
=-\frac{\sqrt{6}}{-0.1}
$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+4\sqrt{6}}{2*-0.2}=\frac{0+4\sqrt{6}}{-0.4}
=\frac{4\sqrt{6}}{-0.4}
=\frac{\sqrt{6}}{-0.1}
$